THE HORSE. 



135 



dence which they still hold to it. The es- 

 sence of this operation is the multiplication 

 of cells by continual subdivision. 



" We have now, on the other hand, to in- 

 quire into the nature of the true Generative 

 process, by which the original germ is en- 

 dowed with its developmental capacity ; 

 and this we shall find to be of a character 

 precisely the opposite of the preceding. 

 For, under whatever circumstances the 

 generative process is performed, it appears 

 essentially to consist in the re-imion of the 

 contents of two cells* of which the germ, 

 v»^hich is the real commencement of a 

 ' new generation,' is the result. This pro- 

 cess is performed under the three following 

 conditions: 1. All the cells of the entire 

 aggregate, produced hy the previous subdi- 

 vision, may be capable of thus uniting with 

 each otiier indiscriminately ; there being no 

 indication of any sexual distinction. This 

 is what we see in the simplest Cellular 

 plants. 2. All the component cells of each 

 organism may, in like manner, pair with 

 other cells, to produce fertile germs ; but 

 there are differences in the shares which 

 they respectively take in the process, which 

 indicate that their endowments are not pre- 

 cisely similar, and that a sexual distinction 

 exists between them, notwithstanding that 

 this is not indicated by any obvious struc- 

 tural character. This condition is seen in 

 the Zygnema and its allies. 3. The gen- 

 erative power is restrict3d to certain cells, 

 which are set apart from the rest of the 

 fabric, and destined to this purpose alone ; 

 and the endowments of the two sets are so 

 far different, that the one fm-nishes the 

 germ, whilst the other supplies the fertiliz- 

 ing influence ; whence the one set have 

 been appropriately designated ' germ-cells ' 

 and the other ' sperm-cells.' Such is the 

 case in all the higher Plants among which 

 a true generative apparatus has been dis- 

 covered ; and also throughout the Animal 

 lungdom. 



* In very rare instances, it is the re-union of the two 

 parts of the contents of the same cell, which had pre- 

 viously tended to separate from each other, as if in the 

 process of subdivision. 



" Thus, then, in the entire process in 

 which a new being originates, possessing 

 lilce structure and endowments with its 

 parent, two distinct classes of actions par- 

 ticipate, — namely, the act of Generation^ 

 by which the Germ is produced ; and the 

 act of Development.) by which that germ is 

 evolved into the complete organism. The 

 former is an operation altogether sui generis ; 

 the latter is only a peculiar modification of 

 the Nuti'itive function; yet it may give 

 oriofin, as we have seen, to new individuals, 

 by the separation (natural or artificial) of 

 the parts which are capable of existing as 

 such. Now, between these two operations 

 there would seem to be a kind of antago- 

 nism. Whilst every act of Development 

 tends to diminish the ' germinal capacity,' 

 the act of Generation reneivs it ; and thus 

 the tree, which has continued to extend 

 itself by budding until its vital energy 

 is well-nigh spent, may develop flowers 

 and mature seeds from which a vigorous 

 progeny shall spring up. But the multipli- 

 cation of individuals does not directly de- 

 pend upon the act of generation alone ; it 

 may be accomplished by the detachment 

 of gemmce., whose production is a simple 

 act of development; and the individuals 

 thus produced are sometimes similar, some- 

 times dissimilar, to the beings from which 

 they sprang. When they are dissimilar, 

 however, the original type is always repro- 

 duced by an intervening act of generation ; 

 and the immediate products of the true gen- 

 erative act always resemble one another. 

 Hence the phrase, ' alternation of genera- 

 tions,' can only be legitimately employed 

 when the term generation is used to desig- 

 nate a succession of individuals, by what- 

 ever process they have originated; an ap- 

 plication of it which cannot but lead to a 

 complete obliteration of the essential dis- 

 tinction which the attempt has been here 

 made to draw between the generative act 

 and the act of gemmation. For when it is 

 said that ' generation a produces genera- 

 tion B, which is dissimilar to itself, whilst 

 generation b produces generation c, which 

 is dissimilar to itself, but which returns to 



