34 Veit BrecnHer WITTROCK. 
When the membrane of the spore has attained a not inconsiderable increase 
in thickness, the spore reposes some time before germinating, and conse- 
quently belongs to the class of spores which is called hypnospores. 
With regard to its origin it may be called an agamospore (from a 
priv., without, and ydéuwocs, marriage), as being formed neutrally without 
any fecundation. — Formation of spores may take place in all the cells 
of the cauloid, in the terminal as well as in the inclosed. As a rule, it 
begins in the youngest, i. e. the terminal, cells; afterwards proceeding 
downwards, or, in other words, basipetally, in the principal filament-as 
well as in the branches. It is these spores which give origin, by their 
germination, to the course of development which has now been briefly 
described. In this manner you will see one neutral generation, forming 
hypnospores, follow upon another in an uninterrupted series, without 
any metagenesis. ‘ 
The reproduction of individuals in Pithophoracee may, however, 
be effected also in another way than by the formation of spores. Besides 
the specimens which form spores there are others, which never do so. 
These, which are, besides, distinguished by a richer ramification, trans- 
form part of their cells into so-called prolific cells. These cells 
are formed simply thus: a common vegetative cell (without suffermg any 
change as to shape) grows richer in chlorophyll-coloured protoplasm 
and starch, and is thus made fit to form a new individual. This the 
prolific cells do, when they have been made free’) by the destruction 
of the mother specimen, by forming a new specimen laterally near their 
top, in the same manner as a branch — and later a system of branches — 
is formed by a cell in the fertile specimens. That the specimens ori- 
ginated by prolific cells have the power of forming spores is certain, 
as well as that specimens forming prolific cells may have been origin- 
ated by spores. I do not know with certainty, whether specimens 
forming prolific cells may have been originated by prolific cells them- 
selves. But it seems to me in no wise improbable. — As to the not 
unfrequent deviations from the scheme of the development given here, 
see the two preceding paragraphs. f 
1) Often two or three prolific cells remain, however, attached to each other. 
