SPIROCHHTA BALBIANII AND SPIROCHATA ANODONTA. 31 
to see some signs of differential motion between the organism 
and its sheath. I have never seen such during my investi- 
gations (text-fig. 7). There is also the question of the longi- 
tudinal division of the membrane. 
Regarding Laveran and Mesnil’s statement as to the non- 
existence of the chromatic border to this membrane, I am 
sorry to have to state that I think they are wrong here, and 
in support of my views I need only refer to the researches of 
Perrin (9) and Swellengrebel (10), and to the fact that all 
Trext-Fic. 7.—a shows the border of the spirally wound membrane 
crossing above and below the body as actually seen in both living 
and stained preparations of Spirochetes. 4. Sheath (“gaine,” Lav. 
et Mesn.). 
research-workers to whom I showed my preparations agreed 
as to the existence of this thick border (cf. Pl. 1, fig. 5; PI. 
3, figs. 18, 20, 36). 
This structure is then a membrane, and is a spirally-wound 
outgrowth of the periplast. It is composed of myoneme 
fibrils, and is contractile, and is the locomotor agent of the 
organism. Its own vibrations are very slight—it is not 
markedly an “ undulating” membrane—and any such slight 
movements of this membrane are independent of those of 
the body. 
It has been recently suggested by Vles.(11) that there is 
