Confervoid Algce. 
51 
into new families. If they are viewed at night, many of the 
fronds may be found at rest at the bottom of the vessel (in the 
daytime they assemble at the side next the light), motionless, 
and with the gonidia rounded and deprived of their nucleus. 
By covering up the bottle from the light, the development of 
the new fronds, which naturally takes place very early in the 
morning, may be retarded so as to be followed during the 
morning until noon. Some of the fronds may be found with 
the gonidia converted into berry-like heaps (fig. 10), others 
with the gonidia already distinct (fig. 11), while many parent 
fronds present the young fronds more or less regularly arranged 
in the softened and expanded parent mass (fig. 12), which ulti- 
mately dissolves and sets them free (fig. 13, 14). They then 
increase in size in proportion to the favourable conditions in 
which they are placed. I have never seen anything like what 
are described by Cohn in Stephanosphcera as ' microgonidia.'* 
When kept for some weeks, an increasing quantity of fronds 
became accumulated at the bottom of the water, and these 
chiefly of the character shown in fig. 17, but devoid of cilia ; 
and while many of them decayed, in others the gonidia be- 
came encysted so as to form globular cellules. Left for a 
fortnight, the water was found without a trace of green colour, 
with merely a brownish sediment at the bottom, upon ex- 
amining which, it was found to contain a large number of 
berry-like forms (fig. 17), with the gonidia not only encysted, 
but with their contents converted into a red, oily, granular 
substance (figs. 21-25), as in the resting-spores of many Con- 
fervoids. The gelatinous frond was here almost dissolved 
away, and a slight pressure was sufficient to detach and 
separate the cellules, which are doubtless resting-spores, and 
destined to become subsequently developed into new fronds. 
This remains to be decided. 
The organism thus described is a well-marked and distinct 
species, very different from Volvox and Gonium^ but approach- 
ing near to Stephanosphcera. The form which produces the 
resting-spores, after losing its cilia, is Kiitzing's Botryocystis 
Morum, I have met with a form like this not unfrequently, 
but never before with the perfect Pandorina. Mr. Pollock tells 
me that he has collected from the same pond for some years 
past, but never found Pandorina before, and yet it colours 
the water green this season. Volvox seems, in like manner, to 
come and go at intervals of years, its revivification from the 
resting-spores depending much on external conditions. 
* * Ann. Nat. Hist.,' 1. c. In a letter received from Professor A. 
Braun since the above was written, he speaks of the forms with small 
gonidia (figs. 7 — 9) as the ' microgonidial' form. A. H., June, 1856. 
VOL. IV. / 
