The tendency of the germ to reproduce the characteristics of its immediate parents, combined lit the case of sexual generation with the tendency to reproduce the character istic of the male. is the source of the singular phenomena of hereditary tran&ntimion. No structural modification is so slight, no functional peculiarity- is so insignificant, in tither parent, that it may not make its appearance in the offspring. But the transtnission of i parental peculiarities depends greatly upon the manner n which they have been acquired. Stich as have arisen naturally, and have been hereditary through many generations, tend to appear in the progeny with great force; while artificial modifica tions, such, for example, as result from mutilation, are rarely, if ever, transmitted. Circumcision through innumerable ancostral generations does not appear to have reduced that rite to a mere formality, as it should have done if the abbreviated prepuce had become hereditary in the Jewish people; while tr.odern lambs are born with long tails, notwithstanding the long-continued practice of cutting those of every generation short. And it remains to be seen whether the supposed hereditary transmission of the habit of retrieving among dogs is really what at first it seems to be. On the other side, Brown Sequard's case of the transmission of artificially induced epilepsy in guinea-pigs is undoubtedly very weighty. In many plants and animals which multiply both asexually and sexually, there is no definite relation between the agamogenetie and the gamogenetic phenomena. The organism may Multiply asexually before. or after, or concurrent with the act of sexual generation. But in a great many of the lower or7.anisms, animal or vegetable, the orgauistn which results from the impregnated germ produces offspring only agamogenetically. This is alternation of generations, which is, strictly, an alternation of asexual with sexual generation, in which the products of the one process differ front those of the other. -The hydrozoa offer a complete series of gradations
between a free self-nourishing organism', through those in which it is free but unable to feed itself, to those in which the sexual eletnents are developed in bodies which resemble free zooids, but are never detached, and are mere generative org,ans of the body on which they are developed.
In the last case, the individual is the total product of the development of the impreg nated embryo, all the parts of which remain in material continuity- with one another. The multiplication of mouths and stomachs in a eonlylophora no more makes it an aggregation of different individuals than the multiplication of segments and legs in a centipede converts that art/wpod into a compound animal. The cordylophora is a differ entiation of a whole into many parts, and the use of any terminology which implies that it results frorn the coalescence of many parts into a whole is to be deprecated. In tor dylophora, the generative organs are incapable of maintaining. a separate existence; but in nearly- all allied hydrozoa the unquestionable homologues of these organs become free zooids, inmany cases capable of feeding. and growing, and developing sexual elements only after they have undergone considerable changes of form. Morphologically, the swarm of ntedustr thus set free from a hvdrozoon are as much organs of the latter as the ratiltitudinons pinnules of a carnal uta, with their genital glands, are organs of the echino derm. Morphologically, therefore, the equivalent of the individual comatula is the hydrozoic stock plus all the inedusze which proceeds from it. No doubt it sounds para doxical to speak of a million of arkides, as parts of one morphological individual; but beyond the momentary shock of the paradox. no harm is done.