HYDRA. 87 



shelter in cellular cavities for temporary retreat, it is evident that the 

 more luxuriant specimens may consist of thousands. 



It is impossible, I say, to anticipate the progeny to come of a single 

 hydra. Propagation seems incessant. I cannot affirm that, as among a 

 multitude of the inferior animals, it is dependent on the seasons. No 

 doubt, there are conditions restraining multiplication ; but some of them 

 are not yet understood. 



On November 21, just two years after the group, Plate XIII. fig. 2, 

 became the subject of observation, a specimen which had dropped from it 

 was found adhering to the side of the vessel. Four or five embryos were 

 now generating from the side of this hydra, which, being one of the largest 

 size, had doubtless given birth to many previous descendants. In April 

 following, the parent and its progeny had augmented to 20 independent 

 hydras, each affixed by its own apex, besides some others, still attached to 

 those from which they were originating. The number amounted to 50 on 

 July 23, when a, the parent of the colony, that is, of the four or five em- 

 bryos on November 21, was much larger than any of its progeny. But in 

 a month it appeared quite distorted, from a new budding of several more 

 embryos unequally advanced. A year after having established itself on 

 the side of the vessel as said above, its descendants — some of the second, 

 perhaps of the third generation — amounted to 73. The size of the parent, 

 a, still predominated over that of any of them except of one, b, which from 

 being fed equalled it. On the 6th of December, 83 were enumerated ; 

 and in addition to this great and rapid increase from one individual, the 

 colony afterwards augmented proportionally. 



The size of the hydra, b, which had equalled that of the parent, a, 

 on November 21, now surpassed it on December 6, and young were bud- 

 ding from its oifspring. The voracity of this creature rendered fish, and 

 flesh, and all other animal substances gratefiil, for it was excessive. Por- 

 tions above its own ordinary dimensions were absorbed at a single meal ; 

 consequently its bulk enlarged over that of a, fed more sparingly. The 

 body, from repletion, swelled to at least thrice its ordinary diameter ; and 

 the animal adhering to the bottom of the vessel, not being suspended 



