184 Transactions of the Society. 



detail has been unusually great, especially since the organism is of 

 extreme minuteness, and complex in the aiTangement of parts. 



I have been able to use in this investigation a 1/10 homo- 

 geneous of large aperture, a 1/12 of 1 • 47 N. A., a 1/25 of 1 • 38 N. A,, 

 a 1/50 of 1 • 38 N.A., and lastly for a little of some part of the work 

 al/6of 1'50N.A. 



All these lenses were made for me by Powell and Lealand. 



Some four years since I was examining cursorily an exhausted 

 maceration of cod-fish which had decomposed in a broth extracted 

 from the boiling of rabbits. The maceration had been for many 

 weeks under examination with another object, but it had now 

 become relatively devoid of the organisms it had contained, and 

 there was, in the glass vessel in which it was contained, a consider- 

 able precipitate at the bottom. It had been kept during the long 

 time it was under examination at a temperatm'e of from 90° to 95^^ 

 Fahr., and it was at the former temperature at the time of which I 

 speak. 



There were still a vast number of Bacterium termo, B. lineola, 

 and Spirillum volutans in the fluid. With a purpose in no way 

 connected with the issue, I examined with a 1/10 homogeneous lens 

 the slightly viscid and granular sediment ; and in two or three of 

 the many globules which I took out with a fine pipette, I detected 

 the presence of an intensely active organism which appeared to 

 present features and movement that I could not reconcile with any 

 septic form familiar to me. It was so small that at first it 

 appeared almost bacterial in its relations ; but it was so involved in 

 the slightly viscid mass, and withal its movements were so quick 

 and constant, that it seemed almost impossible to fairly under- 

 stand it. 



To add to the difiiculty it was manifestly veiy sparsely diffused 

 in the fluid — or rather in the slightly viscid sediment — for it was 

 wholly confined to this ; and it was on an average only once in a 

 dozen drops that two or three of the forms appeared. 



I was examining it upon a cold stage, and as there was at least 

 30^ diflerence in temperature between the stage and the fluid, such 

 organisms as I was able to secure very speedily became enfeebled, 

 and ultimately still. In the slower movements, and in the state of 

 inactivity, I got a glimpse of characters that were, so far as I know, 

 quite unnoted amongst the septic series. 



By a simple arrangement, I adapted a hollow heating plate in 

 the place of the principal part of the glass plate of which my 

 continuous stage was made, as used with the temperature of the 

 surrounding air, and I placed this heating plate in connection mth 

 a vessel of water kept by a mercurial gas regulator, worked with an 

 unchanging gas pressure, at a temperature of 93'' F. 



