EXPERIMENTS ON SPONTANEOUS GENERATION, ETC. 
121 
In the 44 Kesearches ” on the life-history of monads we had 
proved that they could live, thrive, and multiply almost as well 
in Cohn’s 44 nutritive fluid” as in the normal animal infusion. 
This fluid is composed of phosphate of potash, sulphate of 
magnesia, triple basic phosphate of lime, tartarate of ammonia, 
and distilled water. If these ingredients are all mingled the 
fluid becomes speedily charged with bacteria, unless hermetically 
sealed, and sometimes even then. We therefore keep the 
ammonia in a separate solution, mixing them when required. 
A portion of the fine dust of the maceration was now taken 
and thoroughly scattered through the air of the prepared 
chamber. The condensed beam from an oxvhydrogen lime- 
light* was then sent through it. Its line of passage was far more 
brilliantly marked inside the chamber than in the outer air. It 
was deemed inexpedient to insert the fluids while such brilliant 
points were visible in the air, and four hours were suffered to 
elapse. The lime-light beam was still visible with perfect 
distinctness, but its path within the chamber was much less 
brilliant and more homogeneous than it was without. The 
fluids were then carefully mixed, and five small glass basins of 
the mixture were inserted. The whole was undisturbed for five 
days. At the expiration of that time the beam of the lime- 
light sent through the chamber was absolutely invisible, 
although perfectly clear in the open air on both sides of it. 
The fluids were now withdrawn. Ten 44 dips ” were taken 
out of each basin for microscopical examination. In every 44 dip ” 
— that is, fifty in all — one or other of the monads appeared , 
and were in a state of active fission ; and in twenty-seven of 
the 44 dips ” both monads were found. Bacteria swarmed the 
field, which of course I fully expected. 
I now took five other glass vessels, and inserted them with 
great care into the now moteless air of the chamber, and poured 
in, as before, fresh Cohn’s fluid. They were exposed for another 
five days. On careful microscopical examination of seventy-five 
44 dips ” not a single monad of either form appeared ; bacteria 
were feebly present, but of course no steps were taken to guard 
against these, and, as before, they were anticipated. 
The air of the chamber was again impregnated with dust, as 
before suffered for a time to settle, and these same vessels of 
fluid , which had yielded negative results, were again placed in 
the chamber. At the expiration of five days they were again 
examined, and one or other of the monads was found in every 
successive 44 dip I 
Now let it be observed that there can be no possible error a&. 
* This was of course very much less capable of “ searching” than the 
electric beam ; but it served for the rougher end I had in view. 
