AS THE ELEMENTAL GERM OF AN ORGANISM 



347 



mass as the sexual cells, from which the organism was derived, 

 renders this assumption absolutely necessary. 



Secondly, we are forced to this conclusion, when we consider the 

 fact, that in many plants and lower animals, even an extremely 

 small group of cells is able to reproduce the complete organism. 

 When a Funariahygrometrica, is chopped up into very small pieces, 

 and placed upon damp soil, a complete plant grows out of each 

 minute fragment. Similarly, if the fresh water Hydra is cut up 

 into small portions, each develops into a complete Hydra, possess- 

 ing all the properties of its species. Buds may be formed from) 

 the most different parts of a tree by the growth of the vegetative 

 cells ; these buds develop into shoots, which, if separated from 

 the parent, and planted in the earth, can take root and grow into 

 complete trees. In Ccelenterata, in many worms and Tunicates, 

 the asexual mode of multiplication is similar to the vegetative 

 mode, since at each part of the body a bud can be formed, which is 

 able to develop into a new individual. In Bougainvillea ramosa, 

 for instance (Fig. 168), new animals are developed, not only as 

 side branches of the 

 hydroid stock, but 

 also as stolons, which 

 extend themselves 

 like roots upon any 

 surface, and serve to 

 attach the colony. 



Thirdly, many 

 j processes of re- 

 generation, or re- 

 placement of lost 

 parts, prove that in 

 addition to the pro- 

 perties, which are 

 evidently exercised, 

 there must be others 

 which are latent, but 

 which are capable of 

 development under 

 abnormal conditions. 

 For instance, if a 



willow twi{? is Cut FIG. 168. Bougainvillea ramosa (from Lnnp): ?i hy- 



drnnths, which develop into medusa buds mfc; m free 

 Off and placed in medusa Mar geUs ramosa. 



