160 C. A. WATKINS ON YEAST AND OTHER FERMENTS. 



fermentation of cane sugar, that of milk sugar by the gradual de- 

 composition of milk, and also the viscous fermentation of cane 

 sugar ; for although I have seen no notice of any living organism 

 being concerned in this fermentation, I thought it likely that the 

 viscid ropy matter which is formed therein was probably due to 

 some organic growth. 



Now in all these experiments I found that as soon as decompo- 

 sition commenced, or at least was appreciable, but not until then, 

 organic life was found in all the fluids ; that in all cases they ap- 

 peared on the surface before they were seen in the body of the fluid, 

 and that when first discovered they were not in an active condition, 

 but as the decomposition progressed they became so, and moved 

 through the fluid with rapidity, but those at the surface continued 

 to be the most active. These bodies are species of Vibrio and 

 Bacterium. 



The milk used in the experiments was obtained perfectly fresh, 

 and divided into three portions — one containing the cream after the 

 milk had stood 24 hours, the second was simply the skimmed milk, 

 while the third portion was some of the same, with the addition of 

 chalk to neutralise the lactic acid as it was formed. During four 

 days the milk remained sweet, and I detected no organism in any 

 part of it ; but at the end of the fourth day the cream had a sour 

 odour, indicating that lactic acid had been formed, and a small 

 speck taken from the surface with a needle exhibited a mass of 

 Bacterium like bodies which, when some distilled water was passed 

 between the glass slide and cover, swarmed through the fluid with 

 rapid and various capers.* On the fifth day the milk had become 

 sour, and exhibited the same active organs, but in the portion to 

 which the chalk was added they were neither so numerous nor so 

 active. On the eighth day fungus spores and mycelia appeared on 

 the surface of the cream, and the same was noticed, but in a lesser 

 degree, some days afterwards on the two portions of milk ; but as 

 a considerable amount of lactic acid was formed before these objects 

 made their appearance, I do not imagine they were concerned in 

 the fermentation which was going on. 



But it was in the mixture of Boiled Yeast and sugar solution to 

 produce the viscous fermentation that T found these bodies de- 

 veloped most rapidly, for in 24 hours after the mixture was made, 



* The motion here referred to is not due to the currents produced by capillary 

 attraction, evaporation, &c. 



