122 ARCHER, ON STEPHANOSPH/ERA PLUVIALIS. 
processes exist, they are previously drawn in, and the pri- 
mordial cells become rounded—a series of self-divisions sets 
in, similarly to those of the preteen) cells of the perfect 
Stephanosphiera in the first mode of propagation, the cilia 
become lost, and the process is carried on until the same re- 
sult is tiained phat is, until from each Chlamydococcus-.- 
like body an eight-celled, in all respects characteristic, per- 
fect Stephanospheera is produced. I pass by the time 
required for these processes, as well as the hours of the day 
or night with which such developmental changes seem, as in 
other 1 instances, mysteriously associated. 
It may be well here momentarily to draw attention to an 
instance of the great similarity which often exists at certain 
stages of apparently essentially quite distinct organisms, and 
which occasionally more than ordinarily forces itself upon our 
attention. 
I have mentioned that, when I first obtained the material, 
the presence of Gonium pectorale (Khr.) was indicated by 
only a very few specimens indeed; but in about three weeks, 
in one of my bottles, this organism made its appearance in 
very considerable numbers, and they were remarkably fine 
and beautiful examples of this elegant form. In all respects 
they seemed to me to agree w ith the beautiful figures and 
description of Gonium given by Cohn.* I may remark that 
these specimens seemed to me considerably larger and finer 
than those one usually meets with, and more intensely green. 
In the material alluded to, which I possessed, numbers of the 
Gonium were to be found in the various stages of self- 
division figured by Cohn. But likewise a number of the 
specimens were present, as is often the case, from which some 
of the constituent cells of the tablets had been removed by 
some external force, or insufficiency of mutual coherence ; 
and, moreover, what appeared to be these isolated cells (or 
occasionally, indeed, dislocated in twos or in threes) were not 
a few of them to be scen actively urging themselves about in 
the surrounding water. Now, furthermore, some of the old 
globes of the Stephanosphzra occurred upon the slide, and 
some of these showed the primordial cells in the Chlamy- 
donas-like state above adverted to, and these vigorously 
moving up and down within the old, often much collapsed, 
envelope-cell, while some of these had lost their normal 
number of eight, some, indeed, yet retaining only two or 
three. Now, at this point I was quite unable to distinguish 
* € Untersuchungen iiber die Entwickelungsgeschichte der mikroskopis- 
chen Algen und Pilze’ Kaiser. Leopold. -Carol. Akademie der Naturfors- 
cher, Bonn, 1854, p. 163, tab. xviii, figs. 9, 14, 15, 16, 17. 
