22 ZOOPHYTES. 
into the stomach. It appears then that this is the means by which 
the results of digestion, or the nutrient juices, are distributed through 
the zoophyte; and that the sides of the visceral cavity have through- 
out the power of appropriating these chyloid fluids, thus kept in cir- 
culation. There appears to be no system of circulation independent 
of this chyle distribution. 
In certain filiform species (the Tubularie, fig. 1), Lister distin- 
guished a similar motion in the pulpy fluids of the axis, except that, 
instead of vibrating, it was circulatory, part of the fluids moving up 
and part descending by a simultaneous action. ‘They often passed 
into the stomach, and were continuous in their motions with the 
movements of this organ. It appears therefore that the tubular axis 
of these species corresponds with the visceral cavity in the higher 
zoophytes. 
The visceral cavity in the Hydroidea differs widely from the same 
in the Actinoidea, in the absence of vertical fleshy lamelle around 
the sides. Rudiments of these lamellae appear however to have been 
detected by Lister in a Tubularia. It is due to this simplicity of 
structure that the Hydra will live and eat when turned inside out. 
The food of these animals consists of minute animalcules or worms, 
or whatever of animal life is sufficiently small to become their prey. 
The prey is secured usually by means of the tentacles, which entwine 
around it, or together enclose it, and convey it to the mouth. 
14. Reproduction takes place either (1) by ovules proceeding out 
from the sides of the polyps; (2) by lateral buds developing young, 
which, on arriving at maturity, separate from the parent; (3) by 
lateral buds which are persistent; (4) by artificial sections. 
The ovules appear either single or in naked branched clusters; or, 
clustered and enveloped within a common receptacle or ovarian 
vesicle. ‘The figure heading this chapter (10) represents a branched 
cluster as they sometimes appear in the Tubularie. Single ovules 
also are presented by many species of this family: they characterize 
moreover the Hydre. 
The ovarian vesicles, in which a number of ovules are enclosed 
under a common envelope, belong to the Sertularia and Campanu- 
laria families. Some of these vesicles are represented in the following 
figures, and others in figure 2, or enlarged in figure 5. They gra- 
dually develope from the side of a branch, or at times from a creeping 
root-like shoot, which grows outward, like the creeper of a plant, 
sending up its buds and flowers at intervals (fig. 8). The ovules 
