ENDOCRINE FUNCTION OF THE THYMUS GLAND 315 



The first thing needed is to verify the fact that, according to 

 Shimizu, the thymolysis in vivo can effect more than the total 

 removal of the thymus gland which, if carefully done, can be 

 accomplished without any harmful effect whatever Pappen- 

 heimer, '14, and Park, '17). 



2. GENERAL PLAN AND TECHNIQUE 



For the study of any cytolysin the first condition is to obtain 

 a good antibody (amboceptor, cytolysin) of high potency, and 

 the second condition is that the cytolysin thus obtained should 

 show its action clearly in the body of the same kind of animal as 

 that from which the antigen for the immunization has been ob- 

 tained, utilizing the complement of that body, or at least it 

 should be able to combine with the complement of some animal 

 in vitro, to show its action clearly. 



To choose a proper combination of species (one animal for the 

 source of antigen, the other into which the antigen is to be in- 

 jected to obtain a cytolytic serum of high potency), is sometimes 

 difficult without preliminary experiments, because the ease with 

 which different species produce strong antibodies after injection 

 of a given antigen is very variable. 



For the second condition mentioned it should be kept in mind, 

 as Bordet ('06) says, ''que la valeur hemo- ou bacteriolytique des 

 alexines varie d'une espece a I'autre, rein de plus admissible, les 

 d'especes differente n'etant pas entierment identique." 



In general for hemolysis, fresh guinea-pig serum is very potent 

 in activating many sensitized blood-cell complexes, but weak in 

 activating sensitized guinea-pig corpuscles. Often we find that 

 the complement from an animal is entirely impotent or capable 

 of producing only a weak hemolysis of the sensitized cells of its 

 own species, though this is not a general rule (Zinsser). 



The usual technique was employed. For the immunization of 

 the rabbit with thymus we used the thymus from albino rats 

 taken from the stock colony of The Wistar Institute. Rats were 

 chosen between eighty to ninety days, which, according to Hatai 

 ('14), is the period when the thymus gland is largest in the 

 albino rat. 



