XI.] OEGANIC DEVELOPMENT. 129 



into two parts, each of wliicli contains a portion of germinal 

 matter, and continues to live and to grow. The hydra is 

 a little more highly organized than these, and, so far as is 

 known, does not spoiitaneonsly divide, though, as already 

 mentioned, separated parts will live. Its usual mode of 

 propagation is by means of buds, which may be formed on and by 

 any part of its external surface, and rapidly develop into °' 



perfect hydrce, when they detach themselves and creep 

 away. This mode of propagation is, as every one knows, 

 very common among plants, except that the buds of plants 

 seldom detach themselves. 



In these modes of propagation the reproductive power Separate 

 belongs to every part of the organism alike ; but in the or^anf in^ 

 higher animals the reproductive power is confined to the the higher 

 organs of generation, the function of which is to prepare 

 and throw off masses of germinal matter in such a form as 

 shall be best suited for independent life, and, further, to 

 provide the germ with protection and nourishment, either 

 in the ess or in the womb of the mother, until it has 

 attained to some degree of maturity.^ 



We have seen that all living beings whatever have been 

 developed out of perfectly simple germs, and that the 

 germs — the germinal matter — of all species and all classes 

 are to appearance exactly alike. This is no mere inference, 

 but an observed fact. The further question is now sug- Origin of 

 gested, whether this course of development, which is it^aiso^by ^ 

 repeated in the biography of every individual organism, develop- 

 has taken place in the history of every species. Have simple 

 species and classes of organisms, like individuals, been ?fi^'^^' 



1 It ■will be observed that I have adopted Dr. Beale's views on the 

 subject of " germinal matter," as set forth in his edition of Todd and 

 Bowman's Physiology. I regret, however, that Dr. Beale has stated a 

 theory, which I believe to be true and most valuable, in language that can 

 scarcely fail to excite a prejudice against it. He speaks of life as being 

 confined to the germinal matter ; by life, evidently meaning the formative 

 principle. In the sense in which he uses the word, I have shown that 

 I think he has given reasonably good proof that it is so. But it is an 

 unwaiTantable liberty with language, to use the word life in a sense which 

 ■would exclude the contractility of muscle, and the sensibility of nerve, 

 from the denomination of vital functions. 



K 



