Open main menu

Page:Popular Science Monthly Volume 70.djvu/99

This page has been proofread, but needs to be validated.
95
THE PROGRESS OF SCIENCE

Edwin G. Conklin of the University of Pennsylvania, Dr. D. T. MacDougal of the Carnegie Institution, Mr. Charles A. Conant of New York City, and Dr. Simon Flexner of the Rockefeller Institute for Medical Research.

Most of the meetings will be held at Columbia University, but there will also be sessions at the American Museum of Natural History, The Rockefeller Institute for Medical Research, the College of the City of New York, the New York Botanical Garden and elsewhere. These and other scientific institutions of the city have in recent years made extraordinary progress. There is here only space to show several of the buildings of Columbia University, which, having removed to its new site overlooking the city of New York only ten years ago, has now a group of academic buildings in many respects unequalled.

 

THE OPSONIC INDEX OF WRIGHT AND DOUGLAS

Sir Almroth E. Wright, M.D., F.R.S., pathologist to St. Mary's Hospital, London, and late professor of pathology, Army Medical School, Netley, delivered the third course of lectures on the Herter foundation in the Physiological Building of Johns Hopkins Medical School on October 8, 9 and 10, 1906. The subject chosen was 'The therapeutic inoculation of bacterial vaccines and its application in connection with the treatment of bacterial disease.' As this subject is an important elaboration of Metchnikoff's work upon phagocytosis and of Ehrlich's side-chain theory, it may not be out of place briefly to outline from these lectures Wright's method and to cite a few illustrative cases showing the value of this mode of procedure the treatment of certain bacterial diseases by vaccines.

The term opsonin, meaning 'to prepare for a meal,' is given to a recently discovered and important constituent of both normal and immune sera, by means of which bacteria are prepared for phagocytosis. The method of determining the opsonic index is as follows: About five cubic centimeters of blood is withdrawn from a healthy person under aseptic conditions by pricking the finger. This blood is then placed in a glass tube (A), slightly heated to facilitate clotting, and centrifugalized so as to separate the serum from the clot. In a second tube (B) is placed about the same amount of blood, to which is added sodium-citrate solution in order to prevent clotting. By centrifugalizing this there are obtained three layers, i. e., serum, white corpuscles and red corpuscles. The serum it pipetted off and the solution containing leucocytes at once becomes easi'y accessible. A third tube (C) contains an aqueous solution of tubercle bacilli. This is also centrifugalized in order to get a fine suspension. Equal quantities of the serum of a healthy person (A); of white blood corpuscles (B); and of a tubercle bacilli solution (C) are drawn into a capillary tube and freely mixed. They are then placed in an incubator for twenty minutes. A film is next made and stained by any cf the well-known methods of staining for tubercle bacilli. Then the exact number of bacilli found to be present in thirty consecutive multinuclear leucocytes are counted by the aid of an oil-immersion lens—call it in this case X. The process is now repeated, substituting the blood of a patient for the blood of the healthy person, the white corpuscles and aqueous tubercle solution remaining constant in both estimations. The result obtained by counting these latter may be called Y; in that case the opsonic index of the patient's blood is expressed thus, Y/X, which is usually a decimal. The entire process occupies about one hour and a quarter in the hands of an experienced laboratory worker.

The surgeon's idea of curing bacterial diseases, such as scrofulous glands of the neck, seems too often to be that of extirpation, though he does often employ instead of the knife