ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 509 



" Sotto " Bacillus of Silkworms.* — K. Aoki and Y. Chegasaki 

 have studied the question of the pathogenicity to silkworms of Ishiwata's 

 " Sotto " bacillus. The bacillus in question was first described by 

 Ishiwata in 1902, the name " Sotto " meaning "sudden infection" in 

 Japanese. 



When old agar cultures of the Sotto bacillus are administered to 

 silkworms per os, the animals almost invariably die within three hours, 

 this result being brought about through the operation of a toxin 

 elaborated by the bacillus before its introduction, and not through any 

 multiplication of the organisms themselves. If young agar cultures are 

 introduced in large masses, the bacilli, which are relatively atoxic, die 

 out in process of time, and the experimental silkworms are not affected. 

 When worms treated with old cultures manage to survive for a period 

 of from ten to fifteen hours, multiplication of the organisms may be 

 observed in the hasmolymph system, but not in the digestive tract. The 

 germs that are still present in the alimentary canal show commencing 

 degeneration. The invasion of the hamiolyniph system may be ex- 

 plained on the supposition that the resistance of the silkworm is lowered 

 by the action of the bacterio-toxin introduced along with the bacillus. 

 The organism displays particular virulence when it is introduced directly 

 into the hamiolymph system, and in this case the age of the culture does 

 not exercise any influence. 



Leptothrix in Pure Culture f — Y. Kato places on record a case of 

 pleuro-pneumonia caused by leptothrix infection, in which the striking 

 symptoms were fever of long duration, cough, and expectoration. The 

 patient died finally of heart failure. The sputum was throughout of a 

 mucous character, never purulent or blood-stained, and was devoid of 

 elastic fibres or tissue elements. It contained abundant whitish or 

 grey-white leptothrix granules of various shapes and sizes, and was free 

 from Bacillus tuberculosis or other pathogenic organisms. The granules 

 wore round or elliptical, and consisted of three elements — threads, rods, 

 and micrococci. The threads and rods were unbranched and articulated, 

 were Gram-negative, and did not exhibit spores, flagellse, or polar bodies. 

 The organisms were easily obtained in pure growth on various culture 

 media, but especially on media containing sugar or glycerin ; such pure 

 cultures also consisting of threads, rods, and micrococci. This pleo- 

 morphism was especially noticeable in old cultures. 



The leptothrix granules and the derived cultures were found to be 

 pathogenic for mice and guinea-pigs — the inoculated animals dying of 

 chronic septicemia — but were devoid of pathogenicity for rabbits and 

 monkeys and for cold-blooded animals (frogs, goldfish, etc.). Toxin 

 production was never observed. 



The immune serum of rabbits, inoculated with the leptothrix, agglu- 

 tinated the leptothrix, but not other organisms. No agglutination was 

 observed with normal human serum. 



* Mitteil. aus der Med. Fakult. der Kaiserlichen Univ. zu Tokyo, xiii. (1915) 

 pp. 419-39. 



t Mitteil. aus der Med. Fakult. der Kaiserlichen Univ. zu Tokyo, xiii. (1915) 

 pp. 441-7. 



Oct. 80th, 1915 2 N 



