494 The Controversy on Spontaneous Generation : [Oct., 



carefully removed a portion and delineated one of the dry fall- 

 grown filaments with a cluster of spores in its spore-case at the 

 extremity (Fig. 3). Of course I was surprised to find the pro- 

 gress which had "been made in this closed infusion, but on con- 

 sideration it soon occurred to me that if on the one hand the 

 ingress of the first germs was impeded by the cotton-wool, on the 

 other, the same agency prevented their egress when they were 

 produced there, and compelled them to fructify in the vessel in 

 which they were confined ; and moreover, whilst I had been daily 

 disturbing the organizations in the open vessel, and adding distilled 

 water to compensate for evaporation, the other had remained un- 

 disturbed during the whole period. 



Then on examining, for the first time after exposure, the rain- 

 water in the champagne glass, I there discovered large numbers of 

 the same unicellular organisms as in the two infusions, some single, 

 others undergoing subdivision, precisely as in the cases described 

 (Fig. 4), and the natural inference to be drawn from this circum- 

 stance would be, of course, that the mildew fungi were the result, 

 not of spontaneous generation, but of the introduction of germs from 

 without. But here asrain it was necessarv to exercise caution before 

 coming to a conclusion. In the first place, the very fact which 

 I have been trying to demonstrate, viz. the existence of innumer- 

 able atmospheric germs, at once suggested the probability that 

 the germs in the rain-water which stood close to the infusions 

 might have been wafted into it from the fungi growing in those 

 infusions. And secondly, the slightest residuum in my dipping 

 tubes, which I might not have cleansed properly, would suffice to 

 account for the appearance of these cells. These doubts were 

 partly cleared up at once. 



On tasting the infusion which had been covered with cotton, I 

 found signs of acid fermentation, and I examined drops from the 

 surface as well as from the bottom of the liquid, for recent investi- 

 gations on another subject had taught me that during such fermen- 

 tation the biological phenomena vary in different parts of the fluid. 

 At the bottom of the fluid I found clusters of large globular cells 

 (Fig. 6), and on or near the surface groups of smaller elongated 

 ones (Fig. 5). I was at once induced to compare these with the 

 cells of the yeast fungus (Tonrfa cerivisise) which are delineated 

 in the ' Micrographic Dictionary.' and were said to have been 

 found by the observer at the bottom and on the surface of fresh 

 brewer's wort in which fermentation had just commenced. I 

 could hardly find any difference between the two sets of cells, and 

 in both cases those from the bottom of the fluid were round, 

 whilst the surface cells were elongated. This is of course no proof 

 of identity ; and although I strongly suspected that in the one case 

 as in the other the germs had been introduced from without, I 



