166 PATHOGENIC ORGANISMS 



be reduced to 2 c.cms. and only one animal used for the deposit, 

 the other being reserved for a portion of the cream layer. 



On account of its sensitiveness to tuberculosis, the guinea 

 pig is the most suitable animal for inoculation and the best 

 results are obtained with animals weighing from 200 to 300 

 grams. 



Two methods of inoculation are in general use: (a) subcuta- 

 neous injection at the inner side of the left hind leg and (b) 

 intraperitoneal injection through the belly wall. Del^pine 

 prefers to inoculate at the inner aspect of the left leg at the level 

 of the femoro-tibial articulation on account of the comparative 

 results obtained by the uni-lateral development of the lesions. 

 This, he found, was especially noticeable in the early stages 

 with small amounts of infectious material and by noting the 

 extent of the lesion development in two pigs killed after twenty- 

 one and thirty-five days, a rough estimation of the degree of 

 infectivity was procured. In the very early stages the 

 lesions were limited to the subcutaneous tissue and the 

 four groups of lymphatic glands (the popliteal, superficial 

 inguinal, deep inguinal, and the sacro-lumbar) on the same 

 side of the body as the seat of inoculation. Later the retro- 

 hepatic gland and spleen were involved followed by the liver, 

 lungs, bronchial suprascapular, and cervical glands on both 

 sides of the body. Finally there was a more complete invasion 

 of the lymphatic glands in front of the diaphragm on both sides 

 of the body and an involvement of the superficial and deep 

 inguinal and other glands behind the diaphragm on the right 

 side of the body. 



With the intra-peritoneal inoculation the lymphatic glands 

 of the peritoneum and mysentery are first involved, followed 

 by the hver and spleen. The cervical, bronchial, inguinal, and 

 popliteal follow, but the lesion development is bilateral through- 

 out. 



In order to accelerate the development of the disease when 

 the subcutaneous method is used, Block ^^ suggested that the 

 inguinal glands on the inoculation side should be slightly dam- 



