The Muscles of the Adult Honey-Bee(Apis mellifera L.).

By

Guy D. Morison, B.Sc. (Lond.)-

North of Scotland College of Agriculture, Aberdeen.

With 1 Text-figure.

PAET III.THE HEALTHY MUSCLES OP THE ADULT HONEY-BEE.

THE CHEMISTRY OF THE MUSCLES.

CONTENTS.PAGE

T H E C H E M I S T R Y O F T H E M U S C L E S . . . . . . 5 1 1

p H V a l u e s o f M u s c l e . . . . . . . . 5 1 2P r o t e i n s . . . . . . . . . . 5 1 3P i g m e n t . . . . . . . . . . 5 1 5F a t 5 1 6N i t r o g e n o u s E x t r a c t i v e s . . . . . . . . 5 1 7N o n - n i t r o g e n o u a E x t r a c t i v e s . . . . . . . 5 1 7I n o r g a n i c M a t t e r . . . . . . . . . 5 1 8

A P P E A R A N C E O F M U S C L E - F I B R E S U N D E R P O L A R I Z E D L I G H T . . 5 1 9

E F F E C T O F A G E A N D F A T I G U E O N M U S C L E . . . . 5 2 1

T H E O R I E S O F M U S C U L A R C O N T R A C T I O N . . . . . . 5 2 1

S U M M A R Y . . . . . . . . . . . 5 2 3

B I B L I O G R A P H Y . . . . . . . . . . 5 2 4

T H E C H E M I S T B Y O F T H E M U S C L E S .

No physiologist seems to have attempted the detailedchemical analysis of the muscles of any insect. Written know-ledge of the chemistry of the muscles of the adult bee seemslimited to remarks like Holmgren's (1910) when he discusses thealbuminous nature of the sarcosomes of some insects. Strauss(1911) gives some mteresting records of analysis of adult workersand drones, but as whole insects were analysed for glycogen, fat,and nitrogen, the figures cannot be applied to muscles alone.

512 GUY D. MORISON

Aronssohn (1911) analysed the ashes of drones for the elementswhich remained after the dessication of the insects. Since hedoes not state that the drones were washed clean from externalmatter before they were dessicated, I presume that this was notdone. As bees may easily be contaminated with externalmatter, there is the possibility that external matter is includedin his tables of the elements. This might explain the presenceof aluminium and zinc besides various proportions of the otherelements in his tables. Mr. Godden of the Rowett EesearchInstitute kindly discussed with me the results of his ownanalyses (unpublished) of workers and larvae. He too analysedthe ash of unwashed insects. Mr. Duthie carried out some partialorganic and inorganic analyses of bees in the Chemistry Depart-ment, Marischal College. He did not find copper in the ashes.The equipment of our Entomological Department is inadequatefor detailed investigation of the physiological chemistry of themuscles of the bee, so only the bare outline of the subject isattempted in this paper, and all quantitative measurements areomitted. The muscles analysed were very largely fibrousmuscle, owing to the difficulty of obtaining tubular musclesufficient for analysis yet free from other tissue. The thoracesof worker bees were much employed for analysis. In thethorax the chief tissues besides the muscle are the thoracicsalivary glands and ducts and the nerves. It was impossibleto remove the latter completely, but the former were invariablyremoved, though I never obtained a reducing sugar reactionfrom them, but glycogen seems to be present in them sometimesfrom their staining with iodine. Many of the methods em-ployed were microchemical as described in Abderhalden (1912)and elsewhere, otherwise the plan of analysis is such as describedfor vertebrate muscles in books of physiological chemistry,e.g. Cole (1926).

pH Values of Muscle.The hydrogen-ion concentration and its variation in organic

substances is often of importance in chemical analysis, but thismethod of investigation does not seem to have been applied

MUSCLES OF THE BEE 513

in detail to the tissues and secretions of the bee. Till our know-ledge of the physics and chemistry of the muscle of the bee isgreatly extended, the value to be attached to pH readings ofthe muscle can have only a general significance ; especially asmuscle is an unstable complex of many proteins, inorganicsalts, and other substances, each of which would have its ownpH values. Mr. Newlands, of the Agricultural Chemistry De-partment, receives my most cordial thanks for obtaining thepH values of bees' muscles by the method of the quin-hydroneelectrode. The thoraces of a number of bees were removed fromliving insects and crushed in a minimum volume of distilledwater to which the hydroquinone was added. The time fromwhen the bees were alive to when the first pH reading of theirmuscles was taken, was only a few minutes at a room-tempera-ture of about 17° C. The pH of the tissue treated thus was 7-1at the first reading, but altered to 6-6-6-5 after a few minutes.The latter reading seems the more constant. As Mr. Newlandsremarked, these values only indicated that the tissue as a wholewas almost neutral in reaction, though it showed quite a widerange in value.

The most important constituents of living striated muscle ofvertebrates are : (1) proteins, (2) pigment, (3) fat, (4) nitro-genous extractives, (5) non-nitrogenous extractives, (6) inor-ganic matter. The chemical composition of the muscles of thebee will be considered under the above headings.

P ro t e ins .Extracts of both tubular and fibrous muscle as well as por-

tions of the fibres themselves give protein colour-reactions toxanthoproteic, Millon's, biuret, sulphur, and Molisch's tests.The extracts, if freshly prepared, are precipitated by the saltsof the heavy metals, the so-called ' alkaloidal ' reagents, strongalcohol, and heat.

In the fresh muscle extract prepared from the entire thoracesof 100 bees in 5 per cent, magnesium sulphate during 24 hoursin an ice-chest, a coagulation occurs at 55° C. and another at75° C. The coagulum formed at the respective temperatures

514 GUY D. MOEISON

may be analogous with that of paramyosinogen and myosinogenwhich are the chief proteins in living muscles of vertebrates.

Tubular and fibrous muscles after suitable preparation giveall the reactions for myosin or the protein of dead muscle ofhigher animals. The precipitate of myosin dissolved in am-monium sulphate coagulates between 55°-60° C.

Of the various groups of proteins known I have found in themuscles of the bee albumins and globul ins . Albu-minoids or scleroproteins perhaps are present in some of thetendinous attachments of muscle-fibres. Phosphorous is foundin the muscles, but as it may be combined in various ways itdoes not prove the existence of phosphopro te ins . Underconjugated prote ins comes the chromoprotein containingcytochrome (cf. Keilin, 1925-6). The pigment is probably dis-tributed throughout muscle-fibrils and sarcosomes of fibrousmuscle, and from Keilin's records of its wide dispersal in theanimal kingdom it seems plausible that it would be found intubular muscle is sought for carefully.

The glycoprote ins appear as albumen plus carbohydrategroup in the sarcosomes. Nucleoprote ins are probablypresent owing to the large number of nuclei in muscle-fibres,but I have no certain chemical evidence for their existence.Hydrolysed prote ins can be obtained from the nativeproteins by suitable treatment.

During the analysis of fibrous muscle it is impossible to getrid of the sarcosomes, on the other hand it is possible to dissectfree from muscle-fibrils sufficiently large quantities of sarcosomesfor analysis either on a microscope slide or in a test-tube. Ofcourse, however rapidly and frigidly the dissection is accom-plished, the mixture of sarcosomes and collecting fluid is liableto contain blood-plasma and soluble extractives of the muscles.The sarcosomes, when isolated in distilled water, becomespherical (Text-fig. 1) with a shallow cup of protoplasm at onepole and a very delicate wall for the rest of the sphere. Theinterior of the sphere is occupied by a fluid. They show variousmodifications in shape in different fluids (cf. Knoche, 1909 ;Eegaud et Pavre, 1909 ; Bullard, 1912, who describe them for

MUSCLES OP THE BEE 515

various animals). However, it seems to me that their change ofshape is explicable as the reactions of conjugated protein todifferent environments.

The sarcosomes give all the above-mentioned reactions forproteins, including a reddish violet colour to a modification ofAdamkiewicz's reaction which probably indicates that theypossess an indole or skatole radicle in the molecule of one of theirproteins. Molisch's reaction indicates that a protein is combinedto a carbohydrate group.

Text-fig. 1.

Some of the shapes of sarcosomes from living fibrous muscle dissected indistilled water.

P igment .All the tubular muscles when alive are colourless by reflected

and transmitted light. The fibrous muscles in the resting-middle-aged bee of the three castes vary slightly in colour froma pale yellow to a pale orange tinge. The tint is the same forall the muscles of an individual bee. The range in colour doesnot seem to be a chromatolysis due to fatigue, though I havenot been able to tackle the problem of correlation of colour andfatigue. All the progeny of a queen seem constant in the colourof their muscles. Orange-tinted muscles are commoner in blackthan in yellow bees, but there is not a precise correspondencebetween the colour of the integument and muscles. The colouris not seen in the muscles of the pupa or of the very young beein which the muscles are whitish, but from Keilin's work on theblow-fly it seems plausible that the pigment cytochrome would

NO. 287 L 1

516 GUY D. MOHISON

be present in the immature stages of the bee. The colourdevelops gradually apparently with the hardening of the integu-ment, and it persists until death and afterwards for a variableperiod depending on the environment of the muscle. In strongsodium or potassium hydroxide fibrous muscles turn orangered, as Keilin remarked. A yellowish brown colour is seen in thenitrate obtained after crushing fibrous muscle in water, andthis colour persists after long boiling of the nitrate. It is appar-ently due to iron bound in protein which, is not coagulated byheat till a trace of ammonium sulphate is added to the solution.The protein coagulum is brownish and it turns bright blue whentested for the Prussian-blue reaction of iron. The nitrate, afterthe removal of protein coagulum, is usually colourless, but itmay contain traces of iron.

The colour of the living and freshly-examined fibrous muscleis due to the respiratory pigment cytochrome lately describedby Keilin (1925,1926). According to Keilin, cytochrome is veryeasily oxidized. It has the properties of a thermostable peroxi-dase and when oxidized has all the characters of a parahaematincompound. In a reduced state it has a very characteristicabsorption spectrum composed of four main bands, and it is theonly colour seen spectroscopically. When it is oxidized, thebands disappear, and its state, as seen spectroscopically, denotesonly the difference between the rates of its oxidation andreduction.

Through the help of my friend Mr. Griffith of the PhysicsDepartment, we were enabled to see the four absorption bandsof cytochrome approximately in the positions described byKeilin. The bands disappeared with oxidation of the tissue.Our apparatus was a microscope fitted with a spectroscopicprism. Mr. Griffith also receives my warmest thanks for his helpin fitting up apparatus for the examination of muscle bypolarized light.

F a t .In discussing the tracheation of fibrous muscle (Morison,

1928) it was mentioned that very minute quantities of neutral

MUSCLES OF THE BEE 517

fat were sometimes found adjoining the smaller tracheae amongstthe fibres. The fat is not very intimately connected with themuscle-tissue, yet it is the only fat which I have found withfibrous muscle, whilst tubular muscle seems to lack this typeof fat completely. I have not been able to employ methods forthe extraction and subsequent estimation of fats and alliedsubstances, but a great variety of staining methods demon-strated no fat.

The lipins will be included under the heading ' fat '. Someobservers have drawn a certain amount of evidence for thepresence of lipins in sarcosomes and other tissue from the degreeof staining with haematoxylin. Macallum's use of haematoxylinas a means of detecting iron, and Gutstein's paper (1926) on thetheory of haematoxylin staining, show that very little weightcan be attached to such evidence. I am greatly indebted toProfessor Cruickshank of the Bacteriological Department forthe following method of demonstrating the substance lecithin :the stain, light green, is normally insoluble in ether, but passesinto solution in the presence of lecithin. The thoraces of anumber of bees were opened up and extracted in ether for twodays, then the ethereal extract was poured on to an aqueoussolution of light green which coloured the extract. Lecithin inthe vertebrates is derived largely from nervous tissue, so thissource must be considered in the bee. •

Nit rogenous E x t r a c t i v e s .These substances were not investigated in the muscles of

the bee.

Non-ni t rogenous E x t r a c t i v e s .Glycogen was not found in any of the muscles of the bee, by

Best's carmine method of staining or by any other chemicalmethods attempted. Its place is presumably occupied by amonosaccharide, apparently glucose.

It was stated that both muscles and sarcosomes gave apositive reaction to Molisch's test which indicates that a proteinis linked to a carbohydrate group. By rapidly dissecting the

L 1 2

518 GUY D. MORISON

thoraces of twenty to forty bees in 10-20 c.c. cold distilled water,a fluid is obtained which is opalescent to reflected light, butcloudy and tinged faintly brownish by transmitted light. Theopalescence and cloudiness are due to the protein—chieflysarcosomes in suspension—and the brown colour presumably tocytochrome or at least the iron found in it. The bees must befreshly killed, quite clean externally, and their heads and post-abdomens should be plucked off with delicate forceps so thatno food should escape into the oesophagus lying in the thoracicregion. During the dissection the thoracic salivary glands andthe portion of the oesophagus are removed. After decanting,centrifuging, and filtering to remove the muscle-fibres and chitin,the opalescent fluid is boiled till all the protein has coagulated,and the remaining fluid is quite transparent and does not givea protein reaction to biuret. Usually it will be necessary to addmore water before all the protein has coagulated. If the trans-parent fluid is tested by Pehling's or Cole's reactions for reducingsugars, it will give a bright orange precipitate of cuprous oxidewith the former and a yellow precipitate with the latter. Thesugar seems to be glucose. Its osazone with phenyl-hydrazin-hydrochloride is in the shape of yellow, acicular crystalsarranged in sheaves or other patterns like those of glucosazone.It seems reasonable to assume that the sugar has been derivedlargely from the sarcosomes. If the bees used in the experimenthave been dead for a day or longer at room temperature, or ifthe muscles are left soaking for some hours, various chemicalchanges occur in the tissue with the result that the sugar cannotbe demonstrated and that protein is in solution and can only beremoved by heat coagulation after the addition of ammoniumsulphate.

The extraction of sarcolactic acid was not attempted.

Inorganic Mat te r .I cannot give any quantitative measurements of the water

content of muscles, nor can I describe the salts except to writethat variously shaped microscopic crystals will be formed inglycerine if unfixed muscles are mounted in a mixture of dis-

MUSCLES OF THE BEE 519

tilled water and glycerine. The salts would be dissolved in themuscle and in the water, but as the latter evaporates and morepure glycerine is added to the mount the salts become visibleas crystals unless they are soluble in glycerine.

The elements C, O, N, H, S are present in muscle as organicmatter. Iron is easily demonstrable in fibrous muscle, less so intubular muscle, but very clearly in many of the glandularregions. Muttkowski (1921) has stated that copper is presentin the blood of the bee. This leads one to think that it wouldbe found in the tissues, but I have not found a trace of it any-where in the bee either by methods of staining or by a colori-metric test after reducing the tissue of fifty bees to ash. Mr.Welch, of the Agricultural Chemistry Department, also could notfind copper in the ash of fifty bees when he used another verydelicate colorimetric test. Aronssohn (1911) found a very smallpercentage of copper in the ash. Phosphorus would be found inlecithin. It may occur in tissues in the inorganic form of phos-phates and in various complex organic combinations. My ex-periments on the whole show that it exists in the bee, but theyare too long and inconclusive to be worth recording. Chlorine isthe most likely of the halogens to appear in muscle. It may bepresent as a salt, but I can offer no definite proof of its existencein the muscles of the bee, and the same applies to the elementsmagnesium, potassium, and sodium. These elements have beenfound in the ashes of bees.

THE APPEARANCE OF MUSCLE-FIBRES UNDER POLARIZED

LIGHT.

The appearances of muscle-fibres under polarized light havenot been studied in detail by me, since an adequate explanationof all such appearances seems to delve too deeply into thephysics and chemistry of the muscle of the insect to be possiblein the present state of our knowledge. A reader desirous ofpursuing this subject should consult the papers of Engelmann(1873), Merkel (1873), and Van Gehuchten (1886), all of whomexamined the muscles of the bee during their investigations.Schaeffer (1873), Engelmann (1878), Hiirthle (1909), Ebner

520 GUY D. MORISON

(1918), and Jordan (1920) discuss in more or less detail theappearances of insect muscle under polarized light. FinallyStiibel (1923) has written the most scientific and stimulatingpaper on the phenomenon as observed in the muscles of the frog.

My observations may be summarized thus : both tubular andfibrous muscle in the bee show isotropic (not illuminated) andanisotropic (illuminated) discs when examined by polarized lightwith crossed Nicols. The tissue is best examined fresh in wateror salt solution, but two-year-old glycerine mounts of fibresfixed in alcohol and variously stained will often show equallygood contrast. Muscles fixed, stained, and mounted in a mediumlike Canadian balsam do not respond to polarized light.Whether fresh or fixed tissue is examined, not all the fibres willshow equal degrees of contrast—some will be brilliant with theNicols crossed whilst others are invisible and the degree ofbrightness does not depend upon the state of contraction of thefibre. The alary and somatic muscles show strong contrastbetween isotropic and anisotropic transverse discs and a moreobscure longitudinal striation corresponding to their individualfibrils. The cardiac, ventral diaphragm, and alimentary canalmuscles are obscure, the fibrous muscle-fibres are bright andcan be resolved into their component fibrils, but the latter whenseparated are too delicate to be distinguishable. Sarcosomes areinvisible when isolated and they cannot be determined in thefibre. Selenite plates may be used with the Nicols so as to colourthe anisotropic discs, but they do not seem to be an advantage.The tube of the tubular fibre is of some importance optically.

Anisotropy and the depth to which tissue will stain are twoessentially distinct phenomena, but they are often associatedin a fibre in such a way that the darkly stained discs appearanisotropic and the lightly stained discs isotropic, and when thereis a reversal of the striation during contraction there may ormay not be a corresponding displacement of anistropic andisotropic discs. The telophragmata of fresh and fixed tubularfibres are usually in the middle of a broad isotropic band, whilstin fibrous fibres they are often seen as dark transverse lines.

MUSCLES OF THE BEE 521

EFFECT OF AGE AND FATIGUE ON THE MUSCLE.

The effect of age and fatigue on muscle is very difficult tojudge and requires greater detail of technique than I have beenable to bestow on the investigation. If examined by the ordinarymethods, neither tubular nor fibrous muscle seems to show anyvariation from the normal (as described, Morison, 1927, 1928)as the effect of age or fatigue. However, Avith fatigue (cf. Holm-gren, 1908, 1910) there is probably a difference in colour offibrous muscle as well as chemical differences, and with age themuscles may show a state in correlation with the division oflabour in the colony according to the age of the bee (cf. Eosch,1925).

THEORIES OF MUSCULAR CONTEACTION.

The cause of the contraction of muscle is still unknownthough sought actively by physiologists who seem to be ap-proaching close to the object of their search. Amongst thenumber of the older workers who in their quest paid attentionto insect muscle, the names of Engelmann, Kolliker (1888),Schaeffer, Merkel (1881), and van Gehuchten (1886) may bementioned. Engelmann's theory was that a muscle-fibril hadno vital power of movement, but that if it were warmed itabsorbed water from the plasma of the muscle-cell surroundingit. The absorption of water by the fibrils caused them to becomethicker and shorter so that the whole muscle contracted. Theplasma of the muscle-cells was supposed to contain a secretiongiving heat when combined with oxygen and the motor-nerveimpulse was supposed to cause oxygen to unite with the sub-stance. Schaeffer supposed that under certain physico-chemicallaws the isotropic substance flowed into a series of channelsin the anisotropic substance, thereby swelling and shortening thelatter. Merkel (1881) reviews the various theories up to date.Van Gehuchten (1886) considered that the longitudinal strandsof a regular intracellular network were responsible for the con-traction of muscle-fibres. Marshall (1888 and later), workingon the muscles of higher animals, held van Gehuchten's views

522 GUY D. MORISON

essentially, and he stressed the fact that the nerve-fibres seemedto end in contact with the longitudinal bars of the muscle-fibre.

During later years physiologists have paid very little atten-tion to insect muscle. Modern theories of contraction arefounded very greatly on analysis and experimental study ofmuscles of a more convenient largeness than found in mostinsects.

In 1907 Fletcher and Hopkins found that lactic acid accumu-lated in the frog's muscle deprived of oxygen. It had beenknown previously that lactic acid was present in fatiguedmuscles, but the work of these two experimenters opened uppaths for research along which modern workers are treading.

Many physiologists seem to favour the view that the libera-tion of lactic acid in the muscle is the cause of contraction.The acid is supposed to be generated and to produce contractionalong the fibre at certain intervals which presumably coincidewith the transverse striation. The duration of the contractionis very brief, and the lactic acid diffuses away and is neutralizedby the numerous buffers of the vicinity. The muscle will beable to contract repeatedly for a short period of time, even inthe complete absence of oxygen, but finally the accumulation ofacid or the loss of an essential food constituent will result in acondition resembling rigor.

The primary fuel of contraction is a carbohydrate (probablyglycogen in the higher animals, perhaps glucose in the bee) andfat, and presumably protein may be used, should the carbo-hydrate reserve become exhausted. During contraction thetemperature rises, and with the onset of fatigue lactic acidappears and the carbohydrate disappears, whilst imperfectlyknown changes occur in the phosphorous content of the muscle.Oxygen is necessary to restore the muscle completely after con-traction. In its presence lactic acid disappears, carbohydratereappears, carbon dioxide is produced, heat is lost, and themuscle becomes ready to contract again. For a full discussionof the problem the reader is referred to Hill (1926) and to thenumerous papers of his colleagues. Meyerhof (1924) and Harden(1926) should also be consulted. Warburg's theory of the role

MUSCLES OF THE BEE 523

of iron in tissue respiration is of particular interest, consideringthe distribution of this metal in the bee.

Theories to explain how the liberated lactic acid producescontraction of the tissue may be called the surface-tensiontheory, the osmotic theory, the swelling theory, and the theoryof liquid-crystals. Hill (1925) gives reasons for regarding thesurface-tension hypothesis of muscular contraction in its simpleform as untenable. The osmotic theory requires a semipermeablemembrane to enclose each ultimate contractile element, whilstthe lactic acid is formed within the membrane and attracts fluidof higher molecular weight and thereby produces a shorteningof the element. The swelling theory supposes that contractionis due to the colloids of the muscle-cell absorbing water duringthe production of lactic (and phosphoric) acid and that relaxa-tion of the muscle is due to a reversal of the process. Embdenand his school tend to hold this theory. The theory of liquidcrystals was expounded by Garner (1925), who suggested thatthe tension generated on applying a stimulus to muscle-fibreis due to the formation of a solid film of liquid crystals on thesurface of the ultimate fibrils of the muscle. The film is supposedto lie in or upon the anisotropic substance, and the lactic acid isimagined as altering the arrangement of the crystals and soproducing contraction or relaxation. Finally Clark (1927) basesa theory of contraction on X-ray diffraction patterns from re-laxed and contracted fibres. She considers that the substancein the anisotropic state passes abruptly from the liquid crystalto the solid crystal form, as a result of the increase in activitydue to lactic-acid formation.

SUMMARY.

1. The chemistry of the muscles is described in outline. Withit are included pH values and pigment.

2. The appearance of muscle under polarized light is dis-cussed.

3. The effects of age and fatigue on muscle could not bedetermined by the techniques adopted.

4. The theories of muscular contraction are summarized briefly.

524 GUY D. MORISON

BIBLIOGRAPHY.

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Bullard, H. H. (1912).—" On the interstitial granules and fat droplets ofstriated muscle ", ' Amer. Journ. Anat.', 14, pp. 1-46, 7 figs.

Clark, Janet H. (1927).—"A theory of muscle contraction with X-raydiffraction patterns from relaxed and contracted muscles ", ' Amer.Journ. Physiol.', 82, pp. 181-94, 4 figs.

Cole, S. W. (1926).—' Practical Physiological Chemistry ', 7th ed. Heffer,Ltd., Cambridge, England.

Ebner, V. E. v. (1918).—" tlber den feineren Bau der Fliigelmuskelfasernder Insekten ", ' Sitz-Ber. Ak. Wiss. Wien, Math.-nat. Kl.', Abt. I l l ,Bd. 127, S. 3-32, Taf. I.

Engelmann, T. W. v. (1873).—" Mikroskopische Untersuchungen iiber diequergestreifte Muskelsubstanz ", Pfliiger's ' Archiv f. Physiol.', 7, S. 33-76, Taf. II.

(1878).—" Neue Untersuchungen iiber die mikroskopischen Vorgangebei der Muskelcontraktion ", ibid., 18, S. 1-25, Taf. I.

Tletcher, W. M., and Gowland, Hopkins F. (1907).—" Lactic Acid inAmphibian Muscle ", ' Journ. Physiol.', 35, pp. 247-309.

Garner, W. E. (1925).—" The Mechanism of Muscular Contraction ",' Proc. Roy. Soc. London', Ser. B, 99, pp. 40-56.

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(1926).—" The Laws of Muscular Motion (Croonian Lecture) ", ibid.,vol. 100, pp. 87-108.

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(1910).—" Untersuchungen iiber die morphologisch nachweisbarenstofflichenUmsetzungenderquergestreiftenMuskelfasern", ibid., Bd. 75,S. 240-336, Taf. viii-xiii.

MUSCLES OF THE BEE 525

Hiirthle, K. (1909).—" t)ber die Struktur der quergestreiften Muskelfasernvon Hydrophilus im ruhenden und tatigen Zustand ", Pfliiger's ' Archivf. Physiol.', 126, S. 1-164, Taf. i-viii, 5 Textfiguren.

Jordan, H. E. (1920).—"Studies on Striped Muscle Structure. VI. Thecomparative histology of the leg and wing muscles of the wasp, withspecial reference to the phenomenon of stripe reversal during contractionand to the genetic relation between contraction bands and intercalateddiscs ", ' Amer. Journ. Anat.', 27, pp. 1-67, 48 figs.

KeiEn, I). (1925).—" On Cytochrome, a Respiratory Pigment, Common toAnimals, Yeast, and Higher Plants", ' Proc. Roy. Soc. London',Ser. B, 98, pp. 312-39.

(1926).—" A Comparative Study of Turacin and Haematin and itsBearing on Cytochrome ", ibid., vol. 100, pp. 129-51.

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Marshall, C. F. (1888).—"Observations on the Structure and Distributionof Striped and Unstriped Muscle in the Animal Kingdom, and a Theoryof Muscular Contraction ", ' Quart. Journ. Micr. Sci.', 28, pp. 75-107,PL vi.

Merkel, F. (1873).—" Der quergestreifte Muskel. II. Der Contractions-vorgang im polarisirten Licht ", ' Archiv f. Mikr. Anat.', 9, S. 293-307,Taf. xv.

(1881).—"Ueber die Contraction der gestreiften Muskelfaser ", ibid.,Bd. 19, S. 649-702, Taf. xxx.

Meyerhof, O. (1924).—' Chemical Dynamics of Life Phenomena.' Mono-graphs on Experimental Biology. Lippincott Co., Philadelphia andLondon.

Morison, G. D. (1927).—"The Muscles of the Adult Honey-bee (Apis melli-fera L.). Pa r t i . The Healthy Muscles of the Adult Honey-bee. SomaticMusculature ", ' Quart. Journ. Micr. Sci.', 71, pp. 395-463, 12 figs.

(1928).—" The Muscles of the Adult Honey-bee (Apis mellifera L.).Part II. The Healthy Muscles of the Adult Honey-bee. Muscles of theAlimentary Canal, Heart, Diaphragms, and the Reproductive Organs,and the Indirect Muscles of the Wings ", ibid., pp. 563-651, 41 figs.

Muttkowski, R. A. (1921).—" Studies on the Respiration of Insects. I. TheGases and Respiratory Proteins of Insect Blood", 'Ann. Ent. Soc.America ', 14, pp. 150-6.

Regaud, C, et Favre, M. (1909).—"Granulations interstitielles et mito-chondries des fibres musculaires striees ", ' C. R. Acad. Sci. Paris ', 148,pp. 661-4.

Rosch, G. A. (1925).—" Untersuchungen iiber die Arbeitsteilung im Bienen-

526 GUY D. MORISON

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