NEW VIEWS OF ANIMAL TRANSFORMATIONS. 637 



This is the question for our present course of lectures ; but, what- 

 ever the result of our inquiries, it will not invalidate the generality of 

 the principle of association. If, contrary to our past opinions, these 

 higher beings are not simple individuals, we must compare them with 



Fia. 15.— Star-fish. 



those primordial individuals which by combination have produced 

 other types, and which are still found at the base of each of the great 

 divisions of the animal kingdom. Now, how have these individuals 

 arisen ? 



The Hydras and analogous organisms reply. We can cut a Hydra 

 into as many pieces as we like, and each piece, instead of dying, con- 

 tinues to develop and ends by becoming a complete Hydra. It fol- 

 lows that these different parts are independent of each other, like the 

 polyps forming the lowest colonies. Each cell of the Hydra is a true 

 individual, and the Hydras are a colony of these monocellular individu- 

 als as the Siphonophores themselves are colonies of Hydras. Aptitude 

 to social life is communicated by heredity to these cells, as it is com- 

 municated to the polyps. Each cell, each polyp, detached from the 

 colony, is a copy of it, and his after-development tends always toward 

 its formation. At first all the members of a colony are equally apt to 

 reproduce ; then this function is localized like the others, and pertains 

 to some individuals, or some parts, while sexual reproduction becomes 

 more and more important. When the society reaches a certain degree 

 of coherence, these different parts cease to live independently of the 

 others, and can not be separated without danger of dying. 



We see still more clearly in the Sponges their colonial nature. The 

 spongarian individual is formed of two sorts of cellular individuals, the 

 amoeba and infusorial flagellif ere, of which we fiind analogues living, at 

 liberty and in isolation (Fig. 16). The flagelliferous cells of sponges 

 present exceptional features ; they are provided with a nucleus and 

 contractile vesicle, and their unique flagellum is surrounded by a mem- 



