392 W. CECIL BOSANUUET. 



wliat lias been called a Treponema, in wliich the curls are 

 more or less rigid, and a Spirochaete, in which there is 

 more flexibility, may not be dependent to some extent on the 

 medium in which the organism is examined. Accompanying 

 the spirochastes in the water were a considerable number of 

 spirillar organisms, exactly resembling them in microscopical 

 structure (figs. 23, 24 a, h). It seems possible that the segment- 

 ing spirocha^tes (fig. 19) may divide first into short spirilla in 

 some instances before undergoing development into the coccoid 

 stage. At a low temperature the style of the mussel is more 

 slowly dissolved than at the temperature of the room. I have 

 found that, as a rule, this body entirely disappears in about a 

 week or ten days after the mussel is taken up from its native 

 place. One mussel, which was kept for three weeks in an 

 aquarium, where presumably food was plentiful, formed a 

 new style, so far as could be judged, since all the other 

 mussels of the same batch had lost theirs long before. This 

 re-formed style was quite free of spirocluetes. 



My best thanks are due to Prof. Minchin for allowing me 

 to use his laboratory, and for his advice and encouragement; 

 also to Miss Rhodes, who has drawn the illustrations to this 

 paper. 



Lister Institute, 



November 4th. 1010. 



References. 



Fantliiiin. — • P;ivasitology," l!)JU, iii, p. 392. 



Gross. — 'Mittli. aus der Zooloyischen Station zu Napel," 1910, Bd. xx, 



Heft 1. 

 Keysselitz. — 'Aili. a. d. kaisei'liclieiii Gesimdlieit.saiiite.' 19(iH, xxiii, p. 



Leislmian. — " Trans. Soc. Trop. Medicine and Hygiene/ Januai-y, I9l0, 



p. 77. 

 Nnttall, Fantliani, and Porter.— ' Parasitology," 1908, i, No. t. 

 Seliellack. — • Ar)j. a. d. kaiserlielieni Gesiuidbeitsanite," 1909, xxx. p. o79. 



