86 ' ZOOPHYTES. 



A specimen having detached itself from the group represented, 

 Plate XIII. fig. 2, adhered to the side of a jar, and showed symptoms of 

 reproduction on June 26. — Fig. 12. In a week, further developement 

 had followed, fig. 13. By successive evolution, this new subject consisted 

 of the parent and five young sprung of it, on July 15. Twelve individuals 

 with tentacula composed the colony on August 12 ; and twenty could be 

 distinctly enumerated on the 1st of September. But it is singular that 

 the parent hydra, a, as in a preceding example, was now the lowest on the 

 side of the jar ; all its progeny had withdrawn somewhat higher — several 

 considerably so. — Fig. 14. On November 22, they had augmented to 32. 

 About two years subsequent to the fixture of the parent hydra, fig. 12, to 

 the side of the jar, the colony, after many losses, consisted of 45. Such 

 losses are almost inevitable. The longer the period, the greater the chance 

 of deperdition among a number of objects. 



One of this same colony having dropped from its site in October, I 

 transferred it to a watch-glass, which, after the animal had fixed, was kept 

 in an incliaed position, with the convexity upwards. In two months, nine 

 young were generated, and on the first of March following, the augmenting 

 colony consisted of 33 perfect hydrse, almost the whole being established 

 distinctly and separately.— Plate XIII. fig. 15. Their number would have 

 been greater had they not been fed rather sparingly, for the purpose of 

 obtaining satisfactory delineation. Here was a rare example of not one 

 being lost ; and the concavity of the watch-glass, whence the colony was 

 suspended, having been constantly downwards, it remained quite clean. 

 In another month, the number reached 47. 



The multiplication of these creatures, by the budding of each succes- 

 sive generation of the progeny from the side of its immediate parent, 

 brings distant descendants into cotemporary existence. The accumulated 

 multitude originating from a single hydra, can be neither foreseen nor 

 estimated. It must depend on the duration of life and the rate of fertility. 

 We are ignorant of both. There is no reasoning a priori of what shall be 



definite. 



As the enlargement of the Sertularia advances, on corresponding 

 principles, where the hydrse, or at least many of them, enjoy some better 



