S40 BOOK NOTICES

Tubercular diseases of the eye and of the ear are sometimes combined. Cases are quoted of myopia and tuber­cular diseases of childhood. A num­ber of pages are given with case his­tories of myopia in the family. He thinks that the tubercular toxin often selects the one eye without affecting its fellow. Cases are treated by him with doses of antitoxin seemingly causing betterment, and he apparently believes that protection is afforded the child by prophylactic treatment by tuberculin.

H. V. W.

Essentials of Laboratory Diagnosis. Designed for Students and Practi­tioners. Francis Ashley Faught, M. D., Philadelphia. Seventh edition. 78 illustrations, 11 plates. Philadel­phia. F. A. Davis Co. This is a very readable book, being

written in a manner that the general practitioner, specialist, and the student may make a complete review of the progress of laboratory diagnosis to date. Even tho he sends all his speci­mens and laboratory cases to the la­boratory worker for such examina­tion, if he would read this book and then keep it for reference in special cases, he would himself, as well as his patients, gain by its possession. It does not take the place of exhaustive text books, but supplements them by descriptions of simple and reliable methods of obtaining the results of laboratory examinations. The newer methods are well described, the chemi­cals discussed, the microscope and its appurtenances, clinical hematology, the spectroscope, newer methods of blood examination, sphygmomanometry, ani­mal parasites, feces, urine, blood, fundus, milk, etc., and a full appendix, giving laboratory test stains, standard solutions, etc., with a full glossary.

The reviewer found of special in­terest the discussion of blood pressure and the use of the sphygmomanometer to determine it, the description of sero diagnosis as to syphilis, typhoid and other diseases. The book is well printed and sufficiently illustrated.

H. V. W.

CORRESPONDENCE. Asteroid Hyalitis.

To the Editor: The paper of Bach­stez, "Acid fat lime as basis of a species of scintillatio corporis vitrei," ab­stracted in the JOURNAL (Vol. 5, page 414), demands some comment which will clarify facts and thus prevent con­fusion later on. The description given by Bachstez of the condition, is so characteristic as to be identified readily with that of asteroid hyalitis by anyone familiar with this clinical entity created by Benson in 1894. (Trans. Ophth. Soc. U. K., v. XIV, p. 101.) Bachstez himself seems to have felt that his cases belonged in another group than scintillatio and to have intended to ex­press this by the words " . . . a species of. . . ."

In spite of the many cases recorded in the American literature (Holloway, Stark) and the comparative frequency of the symptom complex—I have notes of about eight cases of this kind and none of true scintillatio—this confusion can be explained by the fact that Ben­son's description has found notice in the textbooks only very lately, that of Weeks in 1910 being to my knowledge the first to mention it; even the latest German edition of Fuchs' book by Salzmann does not separate asteroid hyalitis from scintillatio corporis vitrei.

Whether asteroid "hyalitis" is the proper name for the condition is still a question, but until a better one is found, Bachstez' cases ought to be re­corded where they properly belong, un­der asteroid hyalitis. This is of espe­cial importance since they help estab­lish the fundamental fact concerning the chemical composition of the opaci­ties in asteroid hyalitis, announced a few months before by Verhoeff (A. J. O., vol. 4, page 155).

M. FEINGOLD. New Orleans, La.

Radioactive Photometers. To the Editor: In January, 1919, the

AMERICAN JOURNAL OF OPHTHALMOLOGY published an article of mine, "The De­termination of the Minimum Light Sense and Retinal Dark Adaptation

CORRESPONDENCE 841

with the Presentation of a New Type of Photometer."

A radioactive substance "Marvelite" was used as the source of light in the photometer described, and observations made with this instrument, tho elemen­tary in character, certainly confirmed several physiologic principles in the dark adaptation of the retina.

At the time my experimental instru­ment was constructed, the manufactur­ers of "Marvelite" were of the opinion that after a certain initial period of decrease in intensity, the luminosity of the substance would maintain a con­stant value for an indefinite period, and therefore, it seemed to offer an ideal test object for photometric examina­tion, if its intensity could be standard­ized, and this seemed possible.

Circumstances compelled me to post­pone any further investigations with the instrument for a year or more; and when I resumed work with it, I was surprised to find that the luminous discs had decreased markedly in in­tensity, altho they had not been mounted in the instrument until they had been aged over a period which was supposed to give them a constant light value.

I wrote to the Bureau of Standards at Washington for information con­cerning these luminous radium com­pounds, and the following letter ex­plains why it is impossible to construct a satisfactory photometer of the type with which my experiments were con­ducted.

DEPARTMENT OF COMMERCE. Bureau of Standards.

Washington, D. C, June 24, 1922. Dr. Jesse W. Downey. Jr., 529 N. Charles St., Baltimore, Md.

Subject: Use of Radium Compounds with Photometer. Dear Sir:

1. Referring to your letter of June 21 regarding the permanency of self lumi­nous radium compounds, and their pos­sible use as a standard source of light in a photometer, we regret to say that none of these products are sufficiently permanent for the purpose.

2. Because of the pressure of other work, our investigations on self lumi­nous materials have been carried on only in a very fragmentary way, and we have not recently issued any publica­tions on the subject. However, we can say with considerable certainty that none of these materials can be expected to maintain their luminosity for a very long time. In the case of materials used for the illumination of clock faces, instrument dials, and similar purposes, the useful life is ordinarily two to five years, even if the materials are made up of genuine radium. The reason for this relatively rapid decrease seems to be that the material which is made to glow by impact with radium particles becomes exhausted.

3. If you are interested in the details of investigations on the performance of these compounds, we can probably re­fer you to some publications covering researches made elsewhere.

Respectfully, F. C. BROWN, For the Director.

As my paper was abstracted and favorably commented on in several journals and at least one text book, namely, The Year Book of Ophthal­mology, The British Journal of Oph­thalmology, and Elliot's, A Treatise On Glaucoma (Second Edition). I feel that this explanation of my failure to produce a practical photometer war­rants publication.

JESSE W. DOWNEY, JR. Baltimore, Md. Molluscum Contagiosum, Errata.

To the Editor: My father, some time ago, asked me to call your attention to some errors in the abstract on Mollus­cum Contagiosum, which appeared in the digest of literature, O. L., for March. 1922, page 145. He thought it might be possible to make a correction in some future issue, of the whole last sentence of the abstract, which should have read "they conclude:—that mol­luscum contagiosum may exist on the skin of the lids is well known ; that it may cause conjunctivitis is not well known to ophthalmologists; that a single molluscum nodule on or near the