ORGANIZATION OF THE BACTERIA. 41 



EXTRACT FROM PAPER "ON THE EXISTENCE OF 

 FLAGELLA IN BACTERIUM TERMO," BY W. H. 

 DALLINGER, F.R.M.S., AND J. J. DRYSDALE, M.D., 

 F.R.M.S. 



" In the summer of 1872, some very fine specimens of . vohitans came 

 under our notice, and were carefully examined. We were enabled fully 

 to confirm Conn's discovery, and demonstrated repeatedly the presence 

 of a pair of swiftly lashing flagella. The drawing at b, Fig. I, was made 

 from a specimen magnified 1,300 diameters (diminished by ). 



" 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 bac- 

 teria. 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 i\ to the -fa, 

 but with no definite result. Repeatedly 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 crea- 

 ture, 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. 1 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 advantage of throwing the light in 

 only from one direction. We were soon convinced of the exquisite per- 

 formance of the glass when used as an immersion. Amphipleura pellucida 

 was not merely seen to be striated clearly and sharply, but the striae 



1 " M. M. J., vol. x., p. 55 ; and vol. xi., p. 8." 



