134 REPRODUCTION. 



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 

 transformed, by tranverse division, into a number of en- 

 tirely different animals, which is not the case in ordinary 

 metamorphoses. Moreover, the upper segment does not 

 accompany the others in their development. Its office seems 

 to be accomplished so soon as the other segments begin to 

 be independent of it ; being intended merely to favor their 

 development, by securing and preparing the substances 

 necessary to their growth. In this respect it resembles the 

 nurse of the Cercaria. 



348. The 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 organi- 

 zation. Those at the extremity of the 

 branches (), and which appear first, are 

 furnished with long tentacles, wherewith 

 they seize their food (Fig. 143). Those 

 in the axils of the branches, and which 

 appear late, are females (&), and have no 

 such tentacles. Inside of the latter, little 

 spherical bodies are found, each having sev- 

 143. " era! spots in the middle ; these are the eggs. 

 Finally, there is a third form, different from the two preced- 

 ing, produced by budding from the female polyp, to which it 

 in some sort belongs (c). It is within this third sort that the 

 eggs arrive, after having remained some time within the 

 female. Their office seems to be to complete the incu- 

 bation, for it is always within them that the eggs are 

 hatched. 



349. The little animal, on becoming free, has not the 



