The Presidents Address. By Rev. W. H. Bollinger. 181 



been, by means of recent lenses, amongst the last revised. Mr. S. 

 Kent named them Cercomonas typica, and Monas I) ailing eri respec- 

 tively. They are both simple oval forms ; but the former has a 

 flagellum at both ends of the longer axis of the body, while the 

 latter has a single flagellum in front. 



Their principal difference is in their mode of multiplication by 

 fission and in the genetic method of germ production. The former is 

 in every way like a Bacterium in its mode of self-division. It divides, 

 acquiring for each half a flagellum in division, and then, in its highest 

 vigour, in about four minutes, each half divides again. 



The second form does not divide into two, but into many ; and 

 thus, although the whole process is slower, it developes with greater 

 rapidity. But both ultimately multiply, that is, commence new 

 generations by the equivalent of a sexual process. 



These would average about four times the size of Bacterium 

 termo ; and when once they gain a place on and about the putrefy- 

 ing tissues, their relatively powerful and incessant action, their 

 enormous multitude, and the manner in which they glide over, under, 

 and beside each other as they invest the fermenting mass, is worthy 

 of close study. It has been the life-history of these organisms, and 

 not their relations as ferments, that has specially occupied my fullest 

 attention ; but it would be in a high degree interesting if we could 

 discover or determine what, besides the vegetative or organic processes 

 of nutrition, is being effected by one or both of these organisms on 

 the fast-yielding mass. Still more would it be of interest to discover 

 what, if any, changes were wrought in the pabulum or fluid gener- 

 ally ; for after some extended observations I have found that it is 

 only after one or other, or both of these organisms have performed 

 their part in the destructive ferment that subsequent and extremely 

 interesting changes arise. 



It is true that in some three or four instances of this saprophytic 

 destruction of organic tissues, I have observed that, after the strong 

 bacterial investment, there has arisen, not the two forms just named, 

 nor either of them, but one or other of the striking forms now called 

 Tetramitus rostratus and Polytoma uvella ; but this has been in 

 relatively few instances. The rule is, that Cercomonas typica or its 

 congener precede other forms that not only succeed them in pro- 

 moting and carrying to a still further point the putrescence of the 

 fermenting substratum, but appear to be aided in the accomplishment 

 of this by mechanical means. 



By this time the mass of tissue has ceased to cohere. The mass 

 has largely disintegrated, and there appears amongst the countless 

 bacterial and monad forms some one, and sometimes even three 

 forms, that, whilst they at first swim and gyrate, and glide about the 

 decomposing matter, which is now much less closely invested by 

 Cercomonas typica, or those organisms that may have acted in its 

 place, they also resort to an entirely new mode of movement. 



One of these forms is Heteromita rostrata, which, it will be 



