144 THE PRINCIPLES OF IMMUNOLOGY 



there was no permanent improvement. The lack of cellular specificity 

 in such sera is an a priori argument against their use. 



Lens Cytotoxin. The injection of crystalline lens leads to the 

 formation of a cytolysin which is organ specific but not species specific, 

 similar to the production of precipitins by lens protein. Such a cyto- 

 toxin prepared by the use of the crystalline lens of the dog is specific 

 for all mammals, birds and fish and will not act upon other cells from 

 these animals. The fact that the injection of lens into animals of the 

 same species or even into the same individual leads to the production 

 of isocytotoxins and autocytotoxins led Romer to build up a theory 

 concerning the origin of cataract. He suggested that the constant 

 absorption of lens protein from the normal process of tissue wear and 

 tear leads to the development of an isocytotoxin which in later life 

 produces the degeneration of the lens seen in cataract. If such were 

 the case cataract should be a much more frequent complication of age 

 than it is and the lens should be a soft pulpy organ as the result of cyto- 

 lysis. Furthermore, complement is not available in the fluids of the eye 

 and the cytolytic amboceptor is not to be completed in that position. 

 Other theories as to the etiology of cataract are so much more logical 

 that Romer's hypothesis has been practically abandoned. 



Aside from the foregoing example of isocytotoxin and autocytotoxin 

 formation, there are no well-determined illustrations of this phenomenon 

 except for the demonstration by Metchnikoff of isospermatotoxins. 



Bacteriolysins. The death and solution of bacteria in the processes 

 of resistance to disease may be accomplished by the activity of phago- 

 cytic body cells or by virtue of properties of the blood and body fluids 

 similar in every way to those properties which lead to hemolysis. In- 

 deed, the discovery of bacteriolysis antedated that of hemolysis even to 

 the point of understanding the essentials of its mechanism. Nuttall 

 in 1888 demonstrated that fresh normal defibrinated blood has the 

 power of killing bacteria. He set up a series of tubes, each containing 

 the same amount (0.5 to i.o c.c. defibrinated blood) and added to each 

 a small platinum loopful of material from the spleen of a mouse previ- 

 ously inoculated with anthrax. These tubes were incubated and at differ- 

 ent time intervals gelatin plates were made from the tubes and a control 

 made from the splenic material. This showed that as incubation pro- 

 ceeded the bactericidal activity of the blood became apparent. Buch- 

 ner confirmed this fact in 1889 with a slightly different method, 

 whereby a larger amount of blood and bacteria were mixed in one 

 container and incubated and small standard amounts withdrawn by 

 pipette and plated. It was found that if the blood were heated or 

 allowed to stand, its bactericidal power was lost and Buchner named 

 the thermolabile element alexin. He believed it to be of the nature 

 of a ferment, suggested that it might originate in body cells, possibly 

 leucocytes, and recognized the fact that it is not specific. 



The Pfeiff er Phenomenon. The next important advance appeared 

 in the studies of Pfeiffer and his co-workers, who, in 1893, 1894 and 

 subsequently, published the details of what we now speak of as the 



