An Introduction to Zoology. 43 



(though we know not how) to its production ; in the case of the bud, we 

 cannot detect any such preparatory process : the original steps are in both 

 cases inexplicable to our reason, and in the latter invisible to our senses. 

 Multiplication by buds is called gemmiferous reproduction. In the animal 

 .kingdom we seem to have an analogous example in the hydra, or fresh water 

 polypi ; in this case, however, the young individual which at first issues as 

 a bud from the side of the parent trunk, at lengtli detaches itself, and 

 carries on a separate existence. In many lower animals, such as the sea 

 anemone or actinia, such germs, then called gemmules, develope themselves 

 in the interior of the parent, and are ultimately thence projected. This 

 case differs from oviparous reproduction only in the circumstance, that we 

 are unable to detect any previous es.g; but this is only an acknowledg- 

 ment of our ignorance of the first steps of all gemmiferous reproduction, 

 which may nevertheless very closely approximate to the more regular and 

 specific mode of re-production, whereby, as every plant springs from a 

 seed, every animal springs originally ab ovo, from an egg; for this is the 

 universal law ; the deviation of viviparous re-production being only appa- 

 rent : for here also anatomy makes us acquainted with the original egg, 

 although its mode of development is altogether different ; since the vivipar- 

 ous germ requires for its growth not only the scanty supply of nutriment 

 provided in the original eg§, (for every seed or egg consists of a gerra, 

 attached to such an alimentary system,) but in viviparous reproduction 

 the egg being extremely minute, the young require in their first state addi- 

 tional supplies of nutriment, and this they obtain by temporary organs of 

 incorporation with the parent substance, by which they participate in the 

 distribution of its nutritive Huid, the blood. 



Wherever we observe distinct seeds or eggs, we observe also a double 

 system essential to their production ; the one may be called the proliferous 

 system, in which the seed or eggs are originally formed, but still destitute 

 of the vital power of developing the included germs ; the other, the fecun- 

 dating system, essential in some inscrutable manner to the communication 

 of that vivifying power. In vegetables, these organs are included in the 

 pistil and stamina of the flowers j in some instances, both systems are 

 included in the same flower, these are called monoecious ; in others, the 

 proliferous system and the fecundating system occupy the flowers of dis- 

 tinct individual trees of the same species, these are called dioecious. We 

 have the same distinctions in the animal kingdom. In many of the Zoo- 

 phytes, as we have seen, we have only an obscure gemmiferous reproduc- 

 tion ; but in the bivalve moUusca, we have regular monoecious oviparous 

 reproduction. Here the egg appears simply to pass from its first receptacle, 

 through channels in the same individual supplying the fecundating system. 

 The same process continues in two orders of the univalves, the cyclobranchia, 

 or limpet family, and tiie scuti-branchia, or venus-ear family. In other uni- 

 valves of the terrestrial family of snails, and of the aquatic families of the 



