SMALL MASSES OF ZOOGLCEA 185 



which soon pass into a resting stage, and then secrete a transparent 

 gloeal material that binds them together. The question with which 

 we are now concerned is, What are the microscopical changes apt to 

 occur in such a scum or pellicle 1 The scum is confessedly a com- 

 posite zoogloeal layer, and we are not concerned at present with 

 the task of separating or identifying its constituent units. Our 

 object will rather be to see in what way these units combine so as 

 to produce new aggregates, small or large, which either singly, or 

 after many processes of fission, result in the production of different 

 kinds of organisms of higher type. 



Before proceeding to answer this question in some detail, it is 

 only right to point out that it is far from being the rule that the 

 early organisms to appear in all vegetal and animal infusions are 

 Bacteria of different kinds. In some infusions made from carrot 

 or from turnip I have found that minute Torulae are numerous from 

 the first. Then, again, it is not the rule, for all infusions, that the 

 Bacteria which accumulate at the surface should begin at once to 

 assume a zoogloeal development, as is the case with those that 

 reach the surface of hay infusions. On the contrary, in many 

 cases the Bacteria remain separate, for some days at least, so that 

 no coherent membrane is formed till a later period. 



Examination of one of the separate masses of Zooglcea with a 

 high power will show its constitution, and reveal the fact that we 

 have to do with an aggregation of separate Bacteria imbedded in 

 a jelly-like material. The slightly altered Bacteria within the 

 Zoogloea mass are at an early stage plainly to be seen (as in 

 Figs. 10, A and 12, 500), though, later on, they become more or 

 less obscured by reason of progressive molecular changes taking 

 place in the mass during its subsequent transformation. 



Some of these Zoogloea masses, as we shall see, are destined 

 ultimately to be converted into numbers of flagellate Monads or 

 of Amoebae, while others become resolved into heaps of Fungus- 

 germs. I have found it impossible to tell in their early stages from 

 the mere microscopical appearance of the Zoogloea masses 

 whether they are destined ultimately to yield Monads or Fungus- 

 germs, but the latter transformation is undoubtedly the more 

 common.- 



It is important to bear in mind two fairly distinct aspects of the 

 observations about to be recorded, corresponding with different 

 stages of the processes in question. We have to do (i) with the 



