GENERAL CHARACTER OP THE FUNCTION. 949 



sexual process whatever, new beings maybe formed by gemmation or "budding" 

 from the parent-stock, and these, gradually becoming less and less dependent 

 upon it, at last detach themselves and maintain a separate existence. Now this 

 process may be regarded as essentially the same with that of the multiplication 

 of cells by subdivision, which we have seen to be the most common mode of 

 propagation in the simplest cellular Plants ( 104) ; and it differs from the ordi- 

 nary operations of growth and development in no other particular than this 

 that the newly-formed structure, instead of remaining as a constituent and 

 dependent part of the parental fabric, is capable of living independently of it, 

 and of thus existing as a distinct individual when spontaneously or artificially 

 detached. Among the higher tribes of animals, as in Man, this mode of mul- 

 tiplication of individuals does not present itself, at least in the adult state ; for 

 in no instance do we find that a part of the body separated from the rest can 

 develop the organs which are necessary for the sustenance of its existence ; and 

 the power which the organism possesses of regenerating parts which it has lost by 

 disease or accident is restrained within very narrow limits ( 599). But there 

 is good ground to believe that such a multiplication by subdivision may take 

 place at that earliest period of embryonic life at which the germ is nothing else 

 than a mass of cells, wherein no distinction of parts has as yet manifested itself; 

 and that the production of two complete individuals, only held together by a 

 connecting band, may arise from some cause which determines the subdivision 

 of the germinal mass, at the period when its grade of development corresponds 

 with that of the Hydra or Planaria. 1 And this view of the case is confirmed 

 by the facts already stated ( 599), in regard to the higher degree of the re- 

 generating power during embryonic life, infancy, and childhood, as compared 

 with that which remains after the development of the fabric has been completed. 

 955. We have now to consider, however, the proper act of Generation, which 

 uniformly involves the union of the contents of two peculiar cells, which may 

 be designated "sperm-cells/' and " germ-cells." 3 Recent discoveries render it 

 almost certain that this true generative process occurs throughout the Vegetable 

 kingdom, and is not confined, as was formerly supposed, to Flowering Plants. 3 

 It appears to take place in three modes ; which are all, however, but variations 

 of one fundamental plan : 1. In the simplest Cellular Plants, in which every 

 cell appears to possess the same endowments, so that there is no kind of special- 

 ization of function, the generative act consists in the "conjugation" of two of 

 the ordinary cells, between which no difference can be traced. In what may be 

 considered the lowest types of this process, both cells discharge their contents, 

 and the new body or sporangium is formed between them by the mixture of 

 their "endochromes;" each cell appearing to have precisely the same share in 

 the process, so that no distinction of " sperm-cells" and " germ-cells" can be 

 said here to exist. This, however, is precisely what might be expected, when it is 

 remembered that no distinction presents itself between any other organs, such as 

 the root and leaf; each cell having endowments to all appearance identical with 

 those of the rest of the mass. But the generative process, in this which may 

 be regarded as its simplest and most essential form, shows itself to be the pre- 

 cise counterpart of the process of "fission" already described ( 104); for as 

 in the latter one cell divides itself into equal halves, between which no difference 

 can be traced, so, in the act of " conjugation," the contents of two cells, ap- 



1 See Prof. Allen Thomson on "Double Monstrosity," in the "Edinb. Monthly Journ.," 

 June and July, 1844; and Prof. Vrolik's Article " Teratology" in the "Cyclop, of Anat 

 and Phys.," vol. iv. 



2 These terms are adopted from Prof. Owen. See his " Lectures on Parthenogenesis," 

 London, 1849. 



3 For a general account of these discoveries, see the "British and Foreign Medico- 

 Chirurgical Review," Oct. 1849; and " Princ. of Phys., Gen. and Comp.," CHAP, xvin., 

 Am. Ed. 



