Development of Vaucheria Resting-spores. 173 
seen just escaping after rupture of the limiting membrane of 
the sphere. 
In other specimens the change that occurred in these more 
developed pigment Amebe was different. No peripheral 
pigment-free protoplasm was developed, but a central nuclear 
mass of protoplasm, such as may be seen in C and D (x 875), 
was produced. 
All these specimens, as I have said, were found in other- 
wise empty filaments—that is, in filaments denuded of chloro- 
phyll-corpuscles. It is probable therefore that they were 
relatively old and were relicts of some of the earlier germi- 
nations. 
I have only found a single specimen of the pigment 
Amcbe in one of these more developed states while still con- 
tained within an old resting-spore. ‘This specimen is shown 
in fig. 4, HK (x 375), and it may be seen to represent a 
rather abortive attempt at the formation of one of the central 
nuclear masses. 
Both these changes in resting Amabe are very familiar to 
me. ‘They occur frequently in some other kinds of large 
Amebe which are apt to swarm in cells of Nvtelle and in 
Vaucheria filaments when these plants have been kept for a 
short time under certain unnatural conditions. These parti- 
cular Amebe, however, grow most rapidly, while gorging 
themselves with chlorophyll-corpuscles. They then pass into 
a resting condition, and in the course of twenty-four hours or 
less many of them begin to segment peripherally into flagel- 
late monads, while others, lying side by side with them, and 
therefore under similar conditions, for some mysterious reason 
go through the alternative process—that is, each of them 
gives rise to a single central sphere of protoplasm, which 
becomes surrounded by a membrane, and then remains in a 
quiescent condition for three or fourmonths. After this long 
period the substance of the central mass of protoplasm also 
undergoes simultaneous segmentation into a number of 
minute flagellate monads or zoospores *. 
It seems clear, therefore, that the sluggish Amebe whose 
origin has been traced from the mere heaps of pigment- 
granules always present within the resting-spores of certain 
species of Vaucherza tend, after comparatively long periods, 
to pass through developmental phases of a kind so definite 
as to remove all doubt as to the fact of their being independent 
* These changes in Mitella and Vaucheria will be fully described 
in Part IV. of my ‘Studies in Heterogenesis, to be published about 
December next, : 
