106 Transactions of the Boyal Mieroscopical Society. 
diams. (diminished by The only difference between our speci- 
mens and those drawn and described by Cohn was, that we rarely 
saw them with so many turns in the spiral, and the granules were 
not so regular in arrangement, and were often very large. But 
these trifling differences may be accounted for in many ways. 
It is extremely probable, as Cohn suggests, that Ehrenberg's 
Ophidomonas janensis is identical with Spirillum volutans ; and if 
so Cohn only demonstrated what Ehrenberg inferred, from the 
presence of vortical action in front of the creature, viz. that there 
was a flagellum. But Cohn saw, and we confirm the fact, that 
there were two flagella in this form — one at each end. 
Having closed for the present our Monad researches, we have 
been stimulated by the hope that the experience gained by these 
might enable us to prosecute similar investigations into the true 
life history of Bacteria. We have commenced the work this 
summer, and guided by the analogy of S. volutans we have been 
led to make several continuous efforts to find whether or not there 
existed a flagellum or flagella in B. termo. The task of course 
under the best circumstances must be a difficult one, from the 
extreme minuteness of the object. We tried each of Powell and 
Lealand's powers successively, from the yVth to the -sot\ but with 
no definite result. Eepeatedly we both saw vortical action at both 
the distal and proximal end of the termo ; but could not absolutely 
see the organ causing it. But in the process of our investigations 
we made very close and careful observations on the fission of this 
form : we do not purpose now to describe the process, but merely to 
point out a phenomenon that further confirmed our suspicion of the 
presence of an invisible filament. In separating into two, the jointed 
rod of sarcode which is in process of division shakes to and fro at the 
constriction, as if the constricted part were a hinge ; and at length 
a clear separation takes place to quite the length of the original 
termo (sometimes longer), and there is no visible connection between 
them ; nevertheless they act as one creature, so that if one moves 
in any direction the other goes with it just as the two ]parts did 
before separation ; showing that although we cannot see the con- 
nection there must be one ; and the presumption was that it was a 
fine filament, such as we detected in the fission of some monads.* 
We could make no further progress in the question apparently ; 
but our attention was called to the new |th objective prepared by 
Messrs. Powell and Lealand, with which we were soon supplied. 
We used it at first with the " supplementary stage " for very oblique 
illumination, supplied by the same makers ; and this has the advan- 
tage of throwing the light in only from one direction. We were soon 
convinced of the exquisite performance of the glass when used as an 
immersion. Amphipleura pellucida was not merely seen to be 
* ' M. M. J.,' vol. X. p. 55 ; and vol. xi. p. 8. 
