ALTERNATE AND EQUIVOCAL REPRODUCTION. 135 



slightest resemblance to the adult polyp. As in the young 

 Medusa, the body is cylindrical, covered with 

 delicate cilia. After having remained free for 

 some time, the young polyp fixes itself in a flat- 

 tened form. By degrees a little swelling rises 

 at the centre which elongates, and at last forms 

 a stalk. This stalk ramifies, and we soon recog- pj g- 1444 

 nize in it the polyp of figure 143, with the three kinds of 

 buds, which we may consider as three distinct forms of the 

 same animal. 



350. The development of the Campanularia presents, in 

 some respects, an analogy with what takes place in the re- 

 production of plants, and especially of trees. They should 

 be considered as groups of individuals, and not as single 

 individuals. 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 com- 

 monly united in one flower, but which in some instances 

 are separated, as in the hickories and elders.* 



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

 the Polyps, as we see it in the Campanularia ; for example, the liverwort 

 (Marchantiapolymorpha), which has at the base of the cup a little recep- 

 tacle, from the bottom of which little disc-like bodies are constantly form- 

 ing, which, when detached, send out roots, and gradually become complete 

 individuals. Besides that, we find in the Polyps, as in plants, the impor- 

 tant peculiarity, that all the individuals are united in a common trunk 

 which is attached to the soil ; and that all are intimately dependent on 

 each other, so that they perish if severed from the trunk. And if we com- 

 pare, in this point of view, the various species in which alternate reproduc- 

 tion has been observed, we find that the progress displayed in each type 



