5i8 Journal of Agricultural Research voi.xiii, no. io 



The writer performed three times as many infection experiments as 

 those outlined, but since the results were similar, a repetition here would 

 be superfluous. 



In a large experiment like the one given in Table III it is hopeless to 

 analyze thoroughly every death, on account of the enormous work 

 involved; but it is hoped that the number carefully studied will repre- 

 sent a fair sample of all the deaths. Of course every dead caterpillar 

 was examined microscopically, but by careful analysis is meant the 

 systematic study of all species of bacteria isolated. 



An attempt was made to infect lo silkworms (Bombyx mori Linnaeus) 

 and IO army worms {Cirphis unipuncta Haworth) with S. disparts, 

 but the organism does not seem to be pathogenic to these two insects. 

 Guinea pigs and rabbits were forced to drink pure cultures of the 

 organism, but failed to develop any distressing symptoms. If the 

 disease is to be introduced into the field, it appears highly important 

 to determine whether the organism would prove pathogenic to mam- 

 mals like horses, cows, pigs, dogs, and even to human beings. After the 

 guinea pig and rabbit experiment the writer mustered enough courage 

 to drink 5 c. c. of a pure bouillon culture of 5. disparis. Up to the 

 date of writing, about seven months, he has failed to notice any dis- 

 tressing symptoms. 



PATHOLOGY 



The pathology of the Japanese gipsy-moth disease is quite interesting 

 and distinct. Of course during the later stages of the disease practically 

 all of the tissues are affected, but the most striking early changes occur 

 in the muscle tissues. Plate 54, A, is a reproduction of a photomicro- 

 graph of normal and early pathological muscle tissue. The strands to 

 the right and left are normal, whereas the muscle strand in the middle 

 does not show the striae so clearly, and the individual fibrillae seem to be 

 more loosely arranged. Plate 54, B, shows a later stage in the progress 

 of the disease. Here the muscle tissue has lost its striated appearance, 

 which, as can be seen, is due to the fact that the fibrillae have lost their 

 compactness and have separated from one another like threads of cotton. 

 The sarcolemma disintegrates gradually with the rest, and the nuclei of 

 the cells lose their normal positions and become scattered. Finally 

 (PI. 54, C) the muscle tissue disintegrates completely, the fibrillae, etc., 

 are no longer visible, and the whole simulates coagulated protein material 

 with minute granules scattered throughout. When this stage in muscular 

 disintegration has arrived, nearly all of the other tissues have likewise dis- 

 integrated more or less and S. disparis may now be seen scattered every- 

 where. All of the pathological changes cited above are much more 

 strikingly accentuated in artificially infected animals than in those 

 which become infected naturally. This is to be expected, for the reason 



