188 HETEEOGENETIC CHANGES IN 



In the pot from which these specimens were taken, at the end of 

 the seventh day, not a single hypha was to be found from which such 

 germs could have been derived, and all such bodies were similarly 

 absent for many days after, during which, from time to time, I 

 examined the contents of the pot. It was perfectly plain, indeed, 

 that in the thousands of small Zooglcea masses undergoing this 

 change, one had to do with no process of infection. It was clear 

 that the Zoogloea masses were becoming organised simultaneously 

 and throughout their whole substance, and that all the stages of the 

 development of the Fungus-germs, into which they were being 

 transformed, could be more or less plainly traced — the changes in 

 this case taking place without any antecedent minute segmentation 

 of the masses, such as are so common, and which may be seen in 

 a small scale in Fig. ii, C, and in larger masses in Figs. i6 and 17. 



A similar transformation of the Zoogloea masses without ante- 

 cedent segmentation has been seen in other cases, though in none 

 of them have I been able to make out the actual stages of the 

 change anything Uke so plainly as in the specimens represented in 

 Figs. 12 and 13. In one of the cases recently seen, in which the 

 specimens were also taken from a closed pot, the Zoogloea masses 

 as a whole had previously assumed a pale brown tint, and rather 

 large Fungus-germs were formed from their substance. But, 

 again, no hypha of any kind was ever seen among the contents 

 taken from this pot. 



Where a certain amount of segmentation has occurred in the 

 Zoogloea mass and the brown colour is subsequently assumed (as in 

 Fig. II, A, in which the constituent bacteria are still distinct), the 

 rather large brown segments subsequently become resolved into 

 groups of small brown Fungus-germs, such as are shown in Fig. 15 

 (xsoo). 



At other times, segmentation goes on to the production of the 

 ultimate units that are to be formed from the Zoogloea mass before 

 any change in colour occurs. This is shown in Figs. 16 and 17 

 (each X 500). In the first of the two, segmentation is seen to be 

 progressing in a colourless mass ; while in Fig. 17, and especially in 

 the upper half, colourless ultimate segments are separating and 

 becoming brown. In the lower half of the figure, larger masses are 

 separating and becoming brown, as in Fig. 11, A, which will subse- 

 quently divide into from two to five ultimate segments. The same 

 kind of thing occurred in the specimen shown in Fig. 18 ( x 500), 

 which was taken on the twelfth day from a pellicle on another 



