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THE POPULAR SCIENCE MONTHLY. 



for its own growth, it gives rise to buds, which become parasitic 

 hydras like itself, and remain attached to it and share all its ad- 

 vantages. The budding continues until a complicated colony of 

 long proboscides, bodies, and tentacles is formed. A young colony 

 of these larvse is shown in Fig. 12, and an older one in Fig. 13. 



Fig. II'— Outline of a Turritopsis, with parasitic Cunian larvse, 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 ene- 

 mies, diseases, and accidents, and the prospect of long life in- 

 creases 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 perpetua- 

 tion of the species and the welfare of the individual : but this does 

 not hold good of Cunina. The hydra stage has therefore been pro- 

 longed, and the larva has acquired the power to produce other 

 larvse to share its advantages. After a time, however, a flange or 

 collar grows out from the body of each hydra, among the bases of 



