482 Frit sc h,- — The Structure and Development of 
They assume a very irregular shape on coming to rest and 
only move a very little distance away from the mother-cell, 
and some are apparently even whilst still moving surrounded 
by a definite membrane. As far as I could make out, germina- 
tion of these abnormal zoospores does not usually take place h 
Somewhat similar phenomena were seen in a species of 
Oedogonium 2 (Oed. Vaticherii , Braun), which was cultivated 
in a 2 per cent, solution of cane-sugar, placed in direct sun- 
light as much as possible. The contents of the cells had 
rounded themselves off more or less after some days (Fig. 25, o'), 
frequently taking on exactly the shape of a zoospore in course 
of development (see Fig. 25, 0 ; the cell on the right). How- 
ever, the conditions in the sugar solution must be unfavourable 
to the liberation of zoospores, for in most cases the contents 
remained within the mother-cell, surrounding themselves with 
a thick membrane (of two or three layers). Only in one or 
two cases was the liberation of the zoospore observed (Fig. 
25,^), which then took place quite abnormally. It was already 
at that time surrounded by a thick membrane and came to 
rest immediately outside the sporangium. The latter dehisced 
in the ordinary manner, but the zoospore showed no vibrating 
cilia, nor was naturally the formation of the thin membrane, 
usually connected with the liberation of zoospores in Oedo - 
gonium , observed. If the cells are treated with a watery solu- 
tion of Iodine when in this condition, neither the external 
wall of the cell nor the thick membrane of the zoospore is 
perceptibly coloured ; whereas in the cavity of the cell between 
these there lies a substance, which is stained a deep violet 
and which is undoubtedly a kind of mucilage s . This pheno- 
1 Fig. 27 d shows a zoospore of Oed. stagnate, which germinated under relatively 
normal conditions, and which has formed a well-developed rhizoid. The 
irregularity at the apex amounts almost to branching. 
2 From the pools in the Temperate House. The same species later on produced 
oogonia and antheridia in the sugar solution (cf. Klebs, ’ 96 , pp. 279, 280). 
s Klebs (loc. cit., p. 264) took the appearance of this mucilage as indicating the 
commencement of zoospore formation. He says : ‘ Die Hiille hat die Eigenschaft 
sich mit wasseriger Iodlosung violett zu farben, . . . infolgedessen erkennt man die 
Bildung der Zoospore auch dann, wenn diese nicht austritt . . . Gewohnlich verfuhr 
ich dabei in der Weise, dass ich die Faden kurz in konzentrierte Salpeterlosung 
