THE RELATIONS OF PATHOLOGY 115 



larly red corpuscles, as well as for bacteria. The active hemolysins, 

 bacteriolysins, and cytolysins are formed by the union of two dis- 

 tinct bodies, amboceptor and complement, whose properties and 

 affinities are being studied most actively. These substances occur 

 to a considerable extent in the blood of normal animals, and may 

 be induced to develop freely under the stimulation of the injection 

 into animals of large quantities of the cells or bacteria to be acted 

 upon. The fact that hemolytic substances, though of a somewhat 

 different and apparently less complex nature are produced by cer- 

 tain pathogenic bacteria of common occurrence, especially strep- 

 tococci, has given us a new point of departure for the study of the 

 anemia that develops in streptococcal and other infections. By the 

 aid of Ehrlich's theory it has also proved possible to explain the 

 mode of action of the toxic substances in certain venoms, and in this 

 particular field highly valuable facts have been established by the 

 work of Flexner and Noguchi and of Kyes. In certain phases the 

 subject has been simplified by the work of Kyes, who succeeded in 

 showing that a definite chemical substance, namely, lecithin, may 

 act as a complement to amboceptors in venoms, with which it unites 

 as a crystallizable "lecithid." 



The extraordinary complexity of the chemical bodies produced 

 by cellular activity is further illustrated by the group of sub- 

 stances known as agglutinins which have the interesting property 

 of drawing animal as well as bacterial cells together into clumps. 

 Agglutinins may be produced by bacteria as well as by animals. It 

 is more than likely that certain forms of thrombosis met with in 

 infections are caused by agglutination of corpuscles, a form of throm- 

 bosis which has been designated as agglutinative. Experimentally 

 such thrombi are produced with ease by the injection of various 

 agglutinating substances. In animals as well as in man certain infec- 

 tions, e. g., with typhoid bacillus, are associated with the develop- 

 ment of agglutinins having a specific effect upon the bacterium 

 causing the infection. Such agglutinins are being used everywhere 

 for two purposes, (a) to determine the nature of the infection for 

 purposes of clinical diagnosis (as in the agglutination test for typhoid 

 introduced as a clinical measure by Griinbaum) and (6) to identify 

 certain bacteria and establish their relations to the infection. 



Another interesting group of substances of the same general class 

 is formed by the coagulins which have the power of causing certain 

 changes in colloidal albuminous solutions. 



Furthermore it has been found that the serum of an animal treated 

 with a proteid forms precipitates with that one proteid, a property 

 that within certain limits appears to be specific. This has led to the 

 use of specially prepared precipitating serums for the diagnosis of 

 different proteids, e. g., the detection of human blood for medico- 



