THE CROWN ANIMALCULE. 
33 
canal is at the top. In ejection the cloaca is much protruded 
and turned upwards ; the faeces are discharged into the space 
between the body and the case-wall, and then gradually find 
then- way upward and over the rim. The eggs are discharged 
into the same cavity, and there remain till they are hatched ; 
the impressible substance of the gelatinous case yielding to 
make them temporary room; and the young- when born struggle 
gradually upward and outward to liberty. But this I shall 
describe more in detail presently. 
The Nutritive System. — The internal organization of the 
Stephanoceros is complex, but the transparency of the tissues, 
at least when not occupied by the viscera, allows it to be well 
discerned, notwithstanding that the rays of light have to pass 
to the eye through various organs, the integuments, and the 
thick enveloping case. 
The ciliated arms are carried commonly, as I have said, in an 
inarching form (plate iii. a), inclosing a considerable vaulted or 
somewhat ovate space. The setae, or vibrating bristles, are 
arranged in whorls about fifteen or sixteen in number, but their 
closeness at the extreme point precludes the attainment of 
accuracy in counting. The whorls appear in perspective like 
pointed pencils, except on the arm which immediately fronts 
the eye, where they take the appearance of the beards of a 
feather. Those on the inside of the arms are seemingly much 
shorter than those on the outside, and form little brushes 
pointing upward.* Both arms and setae are commonly held 
motionless ; yet there is a manifest vortex in the inclosed 
area ; for small Infusoria approaching are presently drawn in, 
and are driven about in the space. They can enter readily at 
all parts between the arms ; but cannot get out, for if one 
approaches the arms from within it is seen instantly to be shot 
back towards the centre. At first I presumed this change of 
direction to be a spontaneous motion of the imprisoned animal- 
cules, for they were active wayward Monads ; but I perceived, 
after a while, a little inanimate atom have the same action; 
and, after some careful watching, I found that it was caused by 
the setae ; a minute, tremulous, and, as it were, spasmodic 
wave being seen to run along the nearest pencils at the instant. 
A slight jar of the stage or of the table will produce a similar 
wave along all the pencils simultaneously, as well as a momen- 
tary opening of the arm-crown. It is clear, then, that the 
setae, crossing each other, serve as a living net, which admits 
the prey to enter without resistance, but, if touched from within, 
* Leydig thinks that the seta) are planted in a granular stratum external 
to the cuticle, from which they are detached in bundles when subjected to 
slight pressure. 
NO. I. 
D 
