Development of Vaucheria Resting-spores. 171 
outline is so hazy and indistinct. The other small and the 
large sphere had moved comparatively little. 
A rather large sphere of red-orange colour which was a 
long way out in a filament is shown in C (x 375) after it 
had been killed by a weak solution of formalin. The sharp- 
ness of its outline shows that all movements had been stopped. 
In some of the large spheres a very rudimentary development 
takes place. They no longer have the appearance shown in 
C; they seem to have grown somewhat, since around the 
heap of pigment-granules there is a rim of brownish-yellow 
protoplasm, such as is to be seen in D (x 250). This body 
is situated in an empty spore, whose outer membrane shows 
the rupture produced during germination. 
On a single occasion only have I seen one of these pigment- 
spheres encysted. It was situated outside a filament from 
which it had been liberated *. This specimen was in the 
first stock of these germinating resting-spores that was 
examined, and was found after the spores had been in my 
possession in a small bottle for five months. The cyst 
showed a rough tuberculated margin as in E (x 500), and 
the contents were of a blackish-green colour. Although this 
body was outside the filament, there was no room for doubt as 
to its nature. 
I have now examined two or three hundred germinating 
resting-spores of Vaucheria, and in every one of them the 
original pigment-heaps have been seen in one or other of the 
conditions just described—each of them, that is, has been 
found to be included in a small mass of protoplasm which 
has been formed around it in some way during the stages 
immediately preceding the germination of the spore. So long 
as the spore has not sent forth any filaments we see more or 
less ill-defined aggregates of pigment-granules, this being the 
case even up to the stage almost immediately preceding germi- 
nation, such asis shown in Pl. XIV. fig. 1, Dand HE. Onthe 
other hand, as soon as germination has taken place we find 
these pigment-heaps, spherical, sharply defined, enclosed within 
ascanty amount of protoplasm, and exhibiting slight powers of 
independent movement, which, as with other low organisms, 
are destroyed by weak solutions of formalin or osmic acid. 
There cannot be a doubt, in fact, that we have to do with 
* The liberation is easily accounted for, as it very commonly happens 
that after a time the spore itself and one or more of the proximal seg- 
ments of the filament die. All the chlorophyll-corpuscles of such 
segments disappear, while the membranes often become soft and disinte- 
grated. The tormation of dissepiments in both young and old filaments 
of J aucheria is by no means uncommon, 
