ALTEEXATE A1STD EQTIIYOCAL EEPEODUCTTOX. 347 



having several spots in the middle ; these are the eggs. 

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

 ding, produced by budding from the female polyp, to which 

 it in some way belongs (c). It is within this that the eggs 

 arrive, after having remained some time within the female. 

 Their office seems to be to complete the incubation, for it is 

 always within them that the eggs are hatched. 



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

 slightest resemblance to the adult polyp. As in 

 the young Medusa, the body is cylindrical, and co- Fig. 368. 

 veredwith delicate cilia (fig. 368) . After having re- 

 mained free for some time, the young animal fixes it- 

 self and assumes aflattened form. By degrees alittle 

 swelling rises from the centre, which elongates, and 

 at last forms a stalk. This stalk ramifies, and we 

 soon recognize in it the animal of fig. 367, with 

 the three kinds of buds, which we may consider 

 as three distinct forms of the same animal. 



532. The development of the Campanularia presents, in 

 some respects, an analogy to what takes place in the repro- 

 duction of plants, and especially of trees. They should be 

 considered as groups of individuals, and not as single indivi- 

 duals. The seed, which corresponds to the embryo of the 

 polyp, puts forth a little stalk. This stalk soon ramifies by 

 gemmiparous reproduction, that is, by throwing out buds 

 which become branches. But ovulation, or reproduction by 

 means of seeds, does not take place until an advanced period, 

 and requires that the tree should have attained a considerable 

 growth. It then produces flowers with pistils and stamens, 

 that is, males and females, which are commonly united in one 

 flower, but which in some instances are separated, as in the 

 hickories, the elders, the willows, &c. &c.* 



* Several plants are endowed with organs similar to the third form 

 of the Polyps, as seen in the Campanularia : for example, the liver- 

 wort (Marc/iantia polymorpha}, which has at the base of the cup a small 

 receptacle, from the hottom of which little disk-like bodies are constantly 

 forming, these, when detached, send out roots, and gradually become 

 complete individuals. Besides that, we find in some polyps, as in piants, 

 the important peculiarity, that all the individuals are united in a com- 

 mon trunk, which is attached to the soil ; and that all are intimately 

 dependent on each other, as long as they remain united. And if we 

 compare, in this point of view, the various species in which alternate re- 



