468 Fritsch — The Structure and Development of 
the zoospore to commence moving actively. Under abnormal 
circumstances the phenomena connected with the liberation of 
the zoospore and its germination are somewhat modified, and 
I shall refer to some of these modifications below. 
The zoospores were generally allowed to germinate in a slow 
but continuous stream of water on the stage of the microscope 
(Zimmermann, *92, p. 3). In a few cases a weak (2°/ o ) solution 
of cane-sugar was employed. 
1. The Structure of the Young Plants. 
I will commence by describing the structure of the young 
plants in Oed. capillare l , in which the end cell of the filaments 
bears a distinct pointed tip. The species was growing on 
a mass of Nitella syncarpa contained in a glass vessel in 
the Herbaceous Department. When I first observed it, 
numerous young plants of very variable size were attached 
to the sides of the vessel about the level of the water. Most 
of these were unicellular, but some consisted of two or even 
three cells (see Fritsch, 1902, Fig. 23,/) ; all were provided 
with a very prominent tip 2 , which was hollow in its lower 
portion and solid towards the apex. Many of these young 
unicellular plants had again emptied their contents without 
undergoing division, the upper part of the cell-wall, together 
with the tip, being pushed on one side like a hinged lid 3 ; 
in some cases this lid became quite disconnected. Sometimes, 
however, no lid was formed (owing probably to abnormal 
external conditions), and the contents of the cell then became 
rounded off and surrounded themselves with a new membrane, 
being unable to escape as a zoospore (Fig. 25, a ) ; under these 
circumstances a considerable decrease in bulk usually took 
place, the contents only occupying a small portion of the cell. 
It is of interest that I once or twice found that these contents 
had passed over the motile stage and had germinated directly 
1 The germination of the zoospores in this species formed the subject of a note 
in the last Number (cf. Fritsch, ’02). 
2 Not infrequently this tip is dilated into a slight knob towards its apex. 
3 Cf. Fritsch, ’02, p. 414 and Fig. 23 e. 
