122 INFECTION 



Cobra hemotoxin is especially characterized by its power of dissolv- 

 ing the corpuscles of certain species (man, dog, guinea-pig, rabbit) with- 

 out the presence of serum. The explanation of this interesting phenome- 

 non has excited extensive discussion. It is probable that the hemotoxin 

 is in the nature of an amboceptor (Flexner and Noguchi), which is 

 activated, in the absence of serum, by complementing substances (chiefly 

 lecithin) present in the red cells, and in this manner producing hemolysis 

 of these cells. In syphilis the quantity of red-cell lecithin is probably 

 diminished after the primary stage, so that when using definite dilu- 

 tions of venom that are known to hemolyze a certain quantity of normal 

 erythrocytes, an absence of hemolysis of the red corpuscles of a given 

 patient would infer a decrease in complementing lecithin in these cor- 

 puscles and indicate the presence of syphilis. The technic of this reac- 

 tion and its value as a diagnostic procedure will be discussed further on 

 under the head of Venom Hemolysis. 



ENDOTOXINS 



There are a large number of microorganisms, notably the cholera 

 spirillum, the typhoid bacillus, the pneumococcus, and other pyogenic 

 cocci, which, when cultivated and separated from the culture-fluid by 

 filtration, are found to be highly poisonous, whereas the filtrate itself 

 is practically devoid of toxicity except for the soluble hemotoxic sub- 

 stances. In other words, we are dealing with endotoxins, or poisons that 

 are not secreted into the medium in which the bacteria are growing, but are 

 contained more or less firmly within the bacterial body, from which they 

 are separable by some method of extraction or by autolysis, only after 

 death. 



Method of Obtaining Endotoxic Substances. Endotoxic substances 

 are obtained from bacteria by thorough disintegration of the bodies. 

 This is accomplished by various methods: (a) The substances may be 

 found in old cultures as a result of death and disintegration of numbers 

 of bacteria; (6) they may be obtained by suspending the microorganisms 

 in distilled water and shaking in a machine, much as Wassermann and 

 Citron's artificial "aggressins" are prepared; (c) the bacteria may be 

 dried and ground to a fine powder, as in the preparation of Koch's 

 "bacillen emulsion" of tubercle bacilli; (d) MacFadyen freezes masses of 

 bacteria with liquid air, and then grinds them into a fine powder; (e) 

 Conradi recommends autolyzing the bacterial cells in non-nutrient 

 fluids ; (/) Rosenau has studied the endotoxins of pneumococci obtained 

 by alternate freezing and thawing of suspensions in distilled water; (g) 



