SPIROCHHTA BALBIANIL AND SPIROCHZTA ANODONTA. 21 
Comparing the movements of Spirilla with those of Spiro- 
cheetes, it may be remarked that the body of a Spirillum 
while in motion seems more rigid than that of a Spirocheta, 
and, of course, flagella are present in the case of true Spirilla. 
I have carefully noted the movements of Spirilla occurring 
in the hind-gut of the Cockroach for comparison with 
those of Spirocheetes. 
Various scientific workers—both zoologists and bacteriolo- 
gists—to whom I have shown these Spirochetes alive, have 
compared their motion to that of an eel, the embryo of 
Filaria, or Nereis, but with the spiral movement in 
addition. 
The Spirochztes live by endosmosis in the fluids in which 
they swim, and the membrane—although principally an agent 
of movement—may serve to increase the general absorptive 
area of the body. 
THe Mrcuanism or MovEeMENT IN THE SPIROCHATES. 
The subject of the agency and mechanism of movement in 
the parasitic Protozoa is most difficult, and seems to have 
been generally avoided by most authors—indeed, the whole 
- question of the movements of Trypanosomes, Spirocheetes, 
sporozoites and the like, appears to have been little studied 
or described. Regarding the movements of Gregarines and 
their causation we have the accounts of Schewiakoff and 
Crawley, of those of Trypanosomes by Laveran and Mesnil, 
of Coccidian sporozoites by Schaudinn, and the meagre 
account of the movements of “Trypanosoma” balbianii 
by Perrin. These are amongst the principal accounts on this 
subject, and some of them are not very detailed, nor do they 
go to the root of the question. 
This is a problem of the utmost difficulty, and the examina- 
tion of stained preparations, to which so much present-day 
research is often restricted, sheds little light on the matter. 
As a result of much patient observation on living material 
