346 



REPRODUCTION. 



whence the name of Strobila, which was originally given to it, 

 before it was known to be only a transient state of the jelly- 

 fish. The separation constantly goes on, until at last the divi- 

 sions are united by only a very slender axis, resembling a 

 pile of cups placed within each other (i) . The divisions are 

 now ready for separation ; the upper ring first disengages it- 

 self, and then the others in succession.* Each segment (d) 

 then continues its development by itself, until it becomes a 

 complete Medusa (k) ; while, according to recent researches, 

 the basis or stalk remains and produces a new colony. 



529. It is thus, by a series of metamorphoses, that the 

 little animal which, on leaving the egg, has the form of the 

 infusoria, passes in succession through all the phases we have 

 described. But the remarkable point in these metamorpho- 

 ses is, that what was at first a single individual is thus trans- 

 formed, by tranverse division, into a number of entirely dis- 

 tinct animals, which is not the case in ordinary metamor- 

 phoses. Moreover, the upper segment does not follow the 

 others in their development. Its office seems to be accom- 

 plished as soon as the other segments begin to be indepen- 

 dent ; being intended merely to favour their development, by 

 securing and preparing the substances necessary to their 

 growth. In this respect it resembles the nurse of the Cer- 



cana. 



Fig. 367. 



530. The Hydraform-Polyps present phenomena no less 



numerous and strange. The Campanularia 

 has a branching, plant-like form, with little 

 cup-shaped cells on the ends and in the axils 

 of the branches, each of which contains a 

 little animal. These cups have not all the 

 same organization. Those at the extre- 

 mity of the branches (a], and which appear 

 first, are furnished with long tentacles, 

 wherewith they seize their food (fig. 367). 

 Those in the axils of the branches, and 

 which appear late, are females (b), and 

 have no such tentacles. Inside of the lat- 

 ter, little spherical bodies are found, each 



* These free segments have been described as peculiar animals, under 

 the name of Ephyra. 



