82 



Cage B. 



June ^//i.— Inoculated 10 larvae M. disstria as in Cage A. 



June gth. — 6 caterpillars dead. 



June loth. — 3 others dead, the tenth missing (escaped from cage). 



Cage C. (Check). 



June 8th. — Placed several larvae of both species in cage. Injected 

 sterilised water hypodermically. 



June 14th. — All caterpillars still alive and apparently healthy. 



Cage D. 



June loth. — Sterilised a needle, touched culture of organism and 

 pricked a number of caterpillars of each species. 



Jtme 1 7th. — All but 2 dead. 



June 1 2th. — Another dead. 



This experiment was repeated several times and in each case all or 

 nearly all died in about 12 hours after inoculation. 



Cage E. (Check). 



June loth. — Pricked several larvae with sterilised needle. • 

 June 14th. — All alive and healthy. 



The tissues of insects killed by inoculation showed the presence of the 

 organism in very large numbers. 



The above experiments show that death was not caused by the punc- 

 ture of the skin or by injection of liquid, but by disease caused by the 

 specific organism with which the larvae were inoculated and which was 

 in the first place isolated from the tissue of diseased insects collected in 

 the field. It should be observed that after the first isolation a large number 

 of diseased larvae were examined from time to time and it was found 

 that the organism under discussion was apparently not the only cause 

 of disease as in several cases I failed to find it in the diseased tissue. In 

 such cases death seemed to result from a protozoal disease. 



Now it is readily seen that the foregoing experiments, while they 

 establish the pathogenicity of the organism to the tent caterpillars, do 



