HISTORY OP THE ROTIFERA, OR WHEEL ANIMALCULES. 489 
industry, so that in a few minutes a row of pellets was seen, 
forming a portion of a circle around its foot-base. When two 
or three rows were formed, I took occasion to measure the time 
of their construction : one pellet was deposited every minute 
with great regularity. I mixed a little carmine with the water : 
the result was beautiful ; for the dark torrent that poured off 
in front, and the appearance of a rich crimson pellet in the cup, 
were instantaneous. Yet the imbibition seemed deleterious ; 
for the animal would withdraw itself suddenly, after a revolution 
or two, and presently retired sullenly, having laid five or six 
carmine pellets, whose deep tints made them conspicuous on 
the pellucid yellowish ones. Some three hours after, I saw that 
no more had been laid. But in the course of the night the 
case was considerably increased with carmine ; the part so made 
was much less regularly formed of pellets than that composed 
of the natural material ; for the red portion was all confused 
and blended, as it were, into a mass, without distinction of pel- 
lets, though retaining the tubular form. 
A large one, whose case had become accidentally injured 
near the base, so as to be slit for some distance up, protruded 
itself through the opening-, remaining still attached by the foot. 
It did not enter again, but continued for several days, carrying 
on all the functions in the healthiest manner, exposed. It fre- 
quently made pellets, but these were never deposited, but 
allowed to wash off into the water; nor was any attempt 
made to construct a new case. A half-grown one, very active, 
that was near, deposited pellets only rarely, — eight or ten in 
several days ; whence it appears that this process is quite volun- 
tary ; indeed, if it were not so, so rapid is the formation, that 
the tube would be increased beyond all bounds in a very brief 
period of the animal’s life. 
Of the other species of this genus I shall not here say 
much. M. ceratophylli (see fig. c) inhabits a case which is more 
or less of a yellowish-brown tint, but is sufficiently translucent 
to allow the body and foot of the animal to be discerned 
through it, and is never strengthened with anything cor- 
responding to its sisteris ingenious outer wall of self-made 
bricks. It has not attained to that effort of mind ; perhaps 
I might say, it has not sufficient liead-piece ; for if you look at 
its coronal disk, you will see that it is only half as much deve- 
loped as its sister’s ; for, whereas that has four petal-like lobes, 
this has but two. These two form perfect circles united at the 
central point of contact ; or the whole outline may be desig- 
nated a figure of 8. From its symmetry it is a very elegant 
object, especially when the ciliary waves are rotating. The 
gelatinous case in this species is generally much beset with 
