ON POLYPS. 25 



of the affray as the end of the swallowed polyp's existence, but he 

 was mistaken ; after the devourer and his captive had digested 

 the prey between them, the latter was regurgitated safe and sound, 

 and apparently no worse for the imprisonment. 



(33.) We will now proceed to consider the mode of reproduction of 

 these simple animals. When mature and well supplied with food, 

 minute gemmules or buds are seen to become developed from the 

 common substance of the body ; they spring from no particular 

 part, but seem to be formed upon any portion of the general sur- 

 face. These gemmsB appear at first like delicate gelatinous tu- 

 bercles upon the exterior of the parent polyp ; but, as they increase 

 in size, they gradually assume a similar form, become perforated at 

 their unattached extremity, and develope around the oral aperture 

 the tentacula characteristic of their species. 



During the first period of the formation of these sprouts, they 

 are evidently continuous with the general substance from which 

 they arise ; and even when considerably perfected, and possessed of 

 an internal cavity and tentacula, their stomach freely communicates 

 with that of their parent by a distinct opening, so that food 

 digested by the latter passes into the stomach of the young one, 

 and serves to nourish it. As soon as the newly-formed hydra is 

 capable of catching prey, it begins to contribute to the support of 

 its parent ; the food which it captures passing through the aperture 

 at its base into the body of the original polyp. At length, when 

 the young is fully formed and ripe for independent existence, the 

 point of union between the two becomes more and more slender, 

 until a slight effort on the part of either is sufficient to detach 

 them, and the process is completed. 



This mode of increase, when the animals are well supplied with 

 nourishment, and the temperature is favourable, is extremely rapid ; 

 sometimes six or seven gemmse have been observed to sprout at once 

 from the same hydra, and, although the whole process is concluded 

 in twenty-four hours, not unfrequently a third generation may be 

 observed springing from the newly-formed polyps even before 

 their separation from their parent : eighteen have in this manner 

 been seen united into one group, so that, provided each individual 

 when complete exhibited equal fecundity, more than a million 

 might be produced in the course of a month from a single polyp. 



(34.) But perhaps the most remarkable feature in the history 

 of the hydra is its power of being multiplied by mechanical 

 division. If a snip be made with a fine pair of scissors in 



