999 



The I (• (■ li II i (| u (' was as lollows: Ciilliires of lihrohlasls 

 b('lon<^in^ to a 9 years old strain Carrel and Ebcl ing 

 ii;i) were used. The i)rei)aration of the cultures was made 

 in the usual way and the rale of <frowLh measured by 

 projection of the area of jfi'owth. The anti<fc!n used was 

 human ascitic fluid or dog serum. 



The culture selected loi* an exi)erimenl was cut into 

 two equal parts. The one of the fragments was cullivaLecl 

 in a medium consisting of equal volumes of chicken plasma 

 and fresh embryonic tissue juice. The other fragment was 

 [)laced in a nu'dium comi)Ose(l of e{iual volumes of plasma 

 and emi)ryonic tissue juice to which had previously been 

 added the foreign protein in such a proportion that one 

 volume of chicken plasma and one volume of the antigen- 

 embryonic juice mixture would give the desired concen- 

 tration. 



These two cultures or strains wei'e nt)w kept separately, 

 taking care that the control culture was not contaminated 

 by foreign i)r()tein frcMU knives or needles. When transfer- 

 red to a new medium, each of the two cultures was divided. 

 One half culture was used for the continuation of the ex- 

 periment, and the other half was discarded, or used for 

 testing how^ the cultures w'ould act w^hen exposed to the 

 foreign protein in a high concentration. It is necessary 

 to divide the culture every 48 hours, otherwise the central 

 portion of the culture gets thick, badly nourished and fin- 

 ally necrotic. 



In other words, one fragment was cultivated in a medium 

 without antigen (control), the other fragment in a mediimi 

 with antigen (experiment). After 18 hours incubation, both 

 cultures, the experiment and the control, were divided into 

 two. One-half of the exj^erimental culture was transferred 

 to a fresh medium with antigen — and one-half of the 

 control culture to a fresh medium without antigen. Both 

 the experimental and the control strain were cultivated 

 for a long period of time. The remaining halves of the ex- 



