for its own growth, it gives rise to buds, which become parasitic hydras like itself, and remain attached to it and share all its advantages. The budding continues until a complicated colony of long proboscides, bodies, and tentacles is formed. A young colony of these larvæ is shown in Fig. 12, and an older one in Fig. 13.
Fig. 11.—Outline of a Turritopsis, with parasitic Cunian larvæ, copied from McCrady.
The hydra larva of the Liriope is only a short transitional stage in the youth of the adult animal, but in Cunina the larval life has become vastly more important; and this is clearly due to the fact that it has found a home which is extremely favorable to it as a larva, an environment where all its wants are supplied, and where it enjoys so many advantages that the speedy acquisition of the wandering life and high organization of the adult is no longer desirable.
To all ordinary animals the period of infancy is full of danger. Young animals are encompassed on every side by peril from enemies, diseases, and accidents, and the prospect of long life increases enormously as childhood passes and maturity approaches.
Short infancy and rapid development are therefore, in ordinary cases, the conditions which are most favorable for the perpetuation of the species and the welfare of the individual: but this does not hold good of Cunina. The hydra stage has therefore been prolonged, and the larva has acquired the power to produce other larvæ to share its advantages. After a time, however, a flange or collar grows out from the body of each hydra, among the bases of
