Origin of Fungus-germs and Monads. 211 



tlic question of the ultimate destination, or the transforma- 

 tion, of the products of such segmentation. These are two 

 ])arts of the subject that are to some extent distinct, and 

 whicli are well worthy of further separate consideration. 



(1) The Developmental Tendencies in Zooqlceci. — If it be 

 asked, what amount of knowledge do bacteriologists possess 

 on tiiis subject ? the answer must be " next to nothing," 

 if we are to judge from the extreme paucity of information on 

 the subject which is to be found in any of their text-books. 

 Yet if they would only deign to look at what takes place in 

 a filtered hay-infusion, they could very soon satisfy them- 

 selves that Zoogloea masses not only grow rapidly, but 

 undergo definite developmental processes, associated v/ith 

 marked molecular changes, as evidenced by their different 

 behaviour at ditferent stages to logwood or other stains, as 

 well as by the results of microscopical examination. And 

 while these molecular changes are taking place the masses 

 may segment into larger or smaller portions and often into 

 minute spherical or ovoid units, showing that an organizing 

 process is taking place. 



If we look at the constitution of Zoogloea masses as shown in 

 fig. 1, A and B (PI. XIV.), it may be seen that we have only 

 to do with bacteria imbedded in a varying proportion of glceal 

 material. But later on, when the mass has grown, and some 

 amount of segmentation has taken place, as in C, it may 

 often be seen that we have still only to do with aggregates 

 of bacteria. At otlier times, it is true, the molecular changes 

 that have taken place in the mass have so altered its con- 

 stitution (making the segments very refractive) that the 

 included bacteria are no longer recognizable, as in the paler 

 segments shown in D, which soon become resolved into the 

 dark brown Fungus-germs seen by their side. 



But now an important link in the proof of my views may 

 be brought forward. The Zoogloea masses in tiieir early stages 

 are colourless, but a large proportion of them are, as I main- 

 tain^ ultimately destined to give rise to brown Fungus-germs. 

 The assumption of the brown colour may, however, be taken 

 on by the segments of the Zoogloea while they are still only 

 aggregates of bacteria, as may be seen by fig. 2, A, showing 

 nearly spherical segments of a large Zoogloea mass whicli 

 were in different shades of brown, and in some of which the 

 constituent bacteria (now themselves coloured) are plainly to 

 be seen. The same thing occurs not unfrequently in Zoogloea 

 masses which have as yet undergone no segmentation, as in 

 fig. 2, D. In B a small Zoogloea aggregate is seen becom- 

 ing brown, the process being rather more advanced below 



