944 EXPERIMENTAL INFECTION AND IMMUNITY 



EXERCISE 60.-CHEMOTHERAPY 

 EXPERIMENT 113. SALVARSAN 



1. Secure a white rat infected with Sp. recurrens (Sp. Obennayer) and one withT. 

 equiperdum. Also two normal rats. 



2. Examine a drop of blood from the tail of each infected rat and form a rough 

 estimate of the number of parasites per microscopic field. 



3. Inject both rats intravenously with 0.001 gm. salvarsan freshly prepared. 



4. Examine the blood at the end of two hours; after forty-eight, seventy-two, 

 and ninety-six hours. 



5. Inject a control rat intravenously with 0.01 gm. salvarsan and the second with 

 0.05 gm. 



(a) Do the control rats survive? 



(b) Are the infected rats sterilized? 



(c) What is meant by the dosis lethalis? By the dosis curativa 

 By the dosis tolerataf 



(d) Discuss organotropism and parasitotropism. 



(e) Discuss "drug fastness." 



(f) Discuss the question of chemoreceptors. 



