Elements of Applied Microscopy; A Text-Book for Beginners (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ...progress in the study of the phenomena of immunity has been a method for the clinical diagnosis of typhoid fever and certain other diseases. It Fig. 46.--Diphtheria Bacilli (methylene Blue). (After Wesbrook.) Diagrammatic. has been shown that when the animal body is invaded by a parasitic micro-organism, the cells produce in some cases antitoxins which neutralize the poisons of the microbe, and in other cases anti-bodies of another type which have a specific destructive action on the parasite itself. Sometimes the defensive secretions dissolve the foreign cells; sometimes they cause them to clump together in masses and to settle out of the fluid in which they are suspended. In the blood of an individual infected with typhoid fever, bodies of the last type, known as agglutinins, are present; and their clumping reaction is specific for that particular micro-organism. It is true that the blood of a normal individual may contain substances which agglutinate typhoid bacilli, but that of a typhoid patient has the power to such a high degree that it will produce the same effect much more rapidly and in high dilution. In making the diagnosis of a suspected typhoid case, a sample of blood is taken from the lobe of the ear in the usual manner and allowed to clot in a small testtube so that the corpuscles are separated from the clear straw-colored serum. A drop of serum is then mixed on a slide with 40 drops cf a fresh broth culture of the typhoid bacillus. The mixture is covered and examined under the TVmcn oil-immersion objective. At first the bacilli may be seen, after careful focussing, as minute transparent rods, singly, or in pairs and short chains, moving rapidly about across the field of the microscope. If agglutinins be present, the bacteria become motionless...