OBSERVATIONS ON THE GENUS PYTHIUM. 509 



several of the protuberances or lateral outgrowths ; this condi- 

 tion was observed at 2 o'clock, and remained substantially the 

 same at 6 o'clock. At 9.30 next morning the change depicted 

 a' had occurred ; the protoplasm of the hypha had become 

 further retracted — presumably into the now more developed 

 protuberances — and a firm septum was formed nearer the 

 proximal portion of a, a small commencing outgrowth having 

 become emptied of its contents also. Two days later, almost 

 all the protoplasm was thus accumulated into the largest knob 

 of the outgrowths. At b, a similar accumulation has occurred, 

 and in this manner the mycelium becomes irregularly septate 

 independently of the sporangia, conidia, or other reproduc- 

 tive organs. I think the protuberant outgrowths here described, 

 must be looked upon as physiologically important for the 

 accumulation of protoplasm which may serve either for the 

 immediate need of the mycelium, or for the production of 

 oogonia ; since it is certain that the large protuberances may 

 do either of two things, they may put forth ordinary hyph» 

 which merely continue the vegetative growth (fig. 29, d), or 

 several of them develop into oogonia and antheridia (fig. 

 31), apparently at the expense of certain of their neighbours, 

 which they deprive of contents. The above view — that the 

 difference between a young oogonium and a mere bud or 

 conidium, is determined by physiological, and not morpho- 

 logical causes — seems to be almost established when we com- 

 pare the facts just described, with those figured in figs. 31 and 

 35, where the oogonium is distinctly beaked, as if it had 

 begun to grow forth like a conidium, and then been im- 

 pelled to behave as an oogonium. 



The proper zoosporangia of this form could not be dis- 

 tinguished from those described before (figs. 24 to 27), a!nd 

 they were produced in equally enormous quantities. In fio-. 

 30, I have drawn two abnormal types or states, one of which 

 (b) was rather common in my cultivations. In (a), for 

 example, the zoosporangium commenced to form, but 

 proceeded no further than the stage figured; the contents 

 becoming withdrawn and used up later. In the second case 



