188 PROFESSOR ilSTEk. 



professed botanist like my colleague Professor Beiitley. But there 

 Mas no B acterium laciis, and there \\ as no lactic acid fermentation. 



"What inference were we to draw ? Was I to suppose that, 

 although the lactic acid ferment had been excluded, it was im- 

 possible to exclude others; that others were present in the milk 

 as it existed in the cow's udder; or was it that I had not been 

 sufficiently careful ? The latter was the view I was disposed to 

 take. The experiment had been performed in the cow-house, 

 where certainly the air might be supposed to be reeking with 

 organisms. I, therefore, performed the experiment a second 

 time, and this time in the open air. It must be confessed it was 

 not far from the cow-house, and it was a fine day at the very 

 time of the year in which organisms most abound. On this oc- 

 casion, I used twenty-four of the little covered test-tubes; those 

 which you see before you. The result was that this time, 

 again, every glass had organisms developed in the milk which it 

 contained. At the same time, every glass seems to be dif- 

 ferent from all the rest. Such fermentations as there are here, I 

 venture to say, were never seen in milk before. I have brought 

 before you a diagram, showing some of them on a large scale. 

 I want particularly to direct your attention to these strange 

 scarlet spots which occurred in almost all of them. They began 

 as tiny scarlet dots, which spread as fermentative changes capable 

 of self-multiplication in the substance of the milk. Here is one 

 glass that is green, and here is another of an orange-yellow colour. 

 Here are two that have two kinds of filamentous fungi. 1 have 

 not examined them microscopically, but I shall very likely find 

 there are some species that have not been described. 



I felt little doubt that these organisms had got in for want of 

 sufficient care on my part. But how are we to explain these un- 

 heard-of appearances ? Simply this. If the Badenum laciis had 

 been here, it would have taken the precedence of all other organ- 

 isms in its development, and the changes which it would have in- 

 duced would have made the milk an unfit soil for these other 

 numerous species. And the novelty of the appearances depended 

 not on the presence of an unusual variety of organisms, but merely 

 on their having enjoyed an unprecedented opportunity for coming 

 forward. Under ordinary circumstances they would have been 

 smothered — killed — by the efl'ects of the Bacterium laciis and 

 the other ferments that commonly develop in its wake. Such 

 being my belief, I determined to make one more attempt. This 

 time I used again the original twelve glasses, but charged them 

 with greater care. I mentioned that a large proportion of these 

 glasses of the second experiment had scarlet spots ; and in the 

 former experiment in the cow-house the great majority had orange 

 spots, and those, as we have seen, were composed of heaps of 



