266 THE PHENOMENON OF 



size advances with astonishing rapidity, the cells of the 

 net, under favorable circumstances, increase to 600 times 

 the length, and 240,000 times the volume in the course 

 of a few weeks.* 



After this description of the processes taking place in 

 the course of the formation of the gonidia of the Water- 

 net, it is not difficult to perceive its similarity to other 

 modifications of cell-formation by division. Seeking, in 

 the first place, the import of the light spots which 

 characterise the first stage of the new cell-formation of 

 the Water-net, it is beyond doubt that they represent the 

 centres of so many new cells, consequently are either 

 actual nuclei, or, since we cannot detect any defined 

 outlines, accumulations of albuminous substance analo- 

 gous to nuclei. The net-work of granules between the 

 light spots, occupying the boundary-lines of the future 

 gonidia, reminds us of the formerly mentioned production 

 of a zone or plate of granules, appearing in the division 

 of the mother-cells of pollen, as also of the zones of 

 granules in the mother-cells {asci) of the spores of 

 Peziza, and shows that the regions becoming parted off to 

 form new cells are in contact at first. The light streaks 

 which are displayed in the second stage, between the 

 concentrating and isolating tabular portions of the con- 

 tents, appear to be formed by a secreted matter, which is 

 immediately re-dissolved and destroyed, but which effects 

 the solution of continuity between the individual gonidia, 

 and between them and the membrane of the pareut-cell. 



but the latter seems to me more probable. I have also observed similar 

 hermits iu Pediastrum. 



* The entire development of the Water-net to the period of repetition of 

 the formation of gonidia, is completed in about 3 — 4 weeks in cultivated 

 specimens; in the wild state, with more vigorous vegetation, a longer time 

 may perhaps be necessary. The size of the cells at the period of the pro- 

 duction of the net, at which time their shape is almost globular, amounts to 

 ijj milHm.; the fully developed cells frequently exhibit, in the wild state, a 

 length of 5' — 6 millimetres, a thickness of g — J mill. ; when cultivated in- 

 doors, on the contrary, they attain only 1 — If mill., in subsequent genera- 

 tions even only \ — \ mUl. in length, but the propagation, nevertheless, 

 happens at the proper time. 



