32 Annals Entomological Society of America [Vol. XI, 



Suitable checks accompanied all of my experiments. These 

 always died of old age or of Mermis parasitism, but seemed not 

 to suffer naturally from any endemic disease. At times I found 

 some checks prematurely dead, but I traced this to CO2 

 asphyxiation and on replacing my glass plates, which covered 

 the battery jar containers, with cheese-cloth tops, I overcame 

 this difficulty. The glass plates are splendid, however, unless 

 one confines too many insects in one jar. 



As can be seen on examining the tables, I performed a large 

 series of post mortem tests. This means that stained smears 

 were studied and that the material was "plated out," colonies 

 isolated and the species studied on different media, and their 

 bio-chemical characters in carbohydrates, etc., observed. Of 

 course, some of these final tests were finished long after the 

 conclusion of the grasshopper season. It is absolutely impos- 

 sible to perform in a short time, the huge amount of work 

 which experiments of this sort require. 



Conclusions on experiments with cultures "Souche Cham" and 



"Souche Sidiy 



1. "Souche Cham" is pathogenic to M. atlanis, M. blvittatus and 

 M. femur-ruhrum. 



2. "Souche Cham" is not as pathogenic to M. bivittatus and M. 

 femur-rubrum as to M. atlanis. 



3. Passage infections with "Souche Cham" were possible, but no 

 increase in virulence was observed. 



4. The gut of M. atlanis does not rupture, and for this reason the 

 blood and muscle tissue can be used for passage infections. 



5. Extracts from the stomach or intestines can not be used for 

 passage infections. 



6. In food infections the time between inoculation and death is 

 somewhat extended. 



7. "Souche Cham" and "Souche vSidi" are quite virulent even in 

 old cultures. 



8. "Souche Sidi" is not as pathogenic to M. atlanis and M. bivit- 

 tatus as "Souche Cham." 



9. No passage infections with "Souche Sidi" were attempted. 



