Fermentation and Kindred Phenomena. 87 



dividing. As this mode of reproduction occurs very rapidly, the 

 actual rate at which these organisms multiply is something truly 

 startling, and fully accounts for the rapidity with which putre- 

 faction and similar phenomena progress when they have once 

 been set in action. Indeed, it reminds one of the fable of the 

 man who offered to sell his horse for a price to be determined 

 by the nails in its hoofs — ^d. for the first nail, id. for the second, 

 2d. for the third, and so on. You may recollect that if there 

 were in all 24 nails, the horse would have fetched ^*34,947 

 9s. 4d. According to Cohn, under favourable conditions a single 

 bacterium by growth and division could produce in 48 hours 

 the enormous number of 281,500,000,000 individuals! And 

 this rate of development, if carried on for five days, would give 

 sufficient bacteria to fill the ocean. Another estimate is that 

 the progeny of one bacterium which in the course of 24 hours 

 only weighs ^ milligramme, at the end of three days amounts 

 to 7,500 tons. In point of fact, perfectly favourable conditions 

 for the continuous development of these organisms are never 

 actually realised, or at all events for any length of time ; for 

 the rapidity of their multiplication is at once checked as soon 

 as the soil (if I may use the expression) in which they grow 

 begins to be exhausted, and is eventually entirely stopped 

 owing to this cause. Moreover, it would appear as if the sub- 

 stances excreted by the organisms themselves, if not removed, 

 or at all events diluted, act injuriously upon them, and even- 

 tually cause their destruction, or at all events the cessation of 

 their functions ; just as we find that yeast ceases to grow in a 

 sugar solution when the spirit reaches a certain strength, the 

 spirit paralysing or destroying the vitality of the yeast cells. 

 A curious fact in connection with this statement is that in 

 many cases the substances produced by minute organisms are 

 amongst the most active agents for their destruction. I fancy 

 that nearly all excrementitious products are peculiarly fatal to 

 the health of plants and animals producing them. 



Apart altogether from the process of multiplication by fission, 

 we find another distinct method of reproduction among the 

 $chizomycetes % or at all events among some of them. This 



