ORGANS OE GENERATION.
The nature of generation, which is the greatest mystery in the economy of liv ing bodies, is still involved in impenetra ble obscurity. The creation of a living body, that is, its formation by the union of particles suddenly brought together, has not hitherto been proved by any di rect observation. The comparison of this process to that of crystallization is found ed in a false analogy ; crystals are formed of similar particles, attracting each other indifferently, and agglutinated by their surfaces, which determine the order of their arrangement : living bodies, on the contrary, consist of numerous fibres or laminae, of heterogenous composition, and various figures, each of which has its pe culiar situation in relation to the other fibres and laminae. Moreover, from the instant in which a living body can be said to exist, however small it may he, it possesses all its parts ; it does not grow by the addition of any new lamina, but by the uniform orirregular developement of parts which existed before any sensi ble growth.
The only circumstance common to all generation, and, consequently, the only essential part of the process, is, that every living body is attached at first to a larger body of the same species with itself. It constitutes a part of this larger body, and derives nourishment for a cer tain time from its juices. The subsequent separation constitutes birth ; and may be the simple result of the life of the larger body, and of the consequent develope ment of the smaller, without the addition of any occasional action.
Thus the essence of generation con sists in the appearance of a small organ ised body in or upon some part of a larger one ; from which it is separated at a cer tain period, in order to assume an inde pendent existence.
All the processes and organs, which co operate in the business of generation in certain classes, are only accessory to this primary function.
When the function is thus reduced to its most simple state, it constitutes the gemmiparous, or generation by shoots.
In this way the buds of trees are develop ed into branches, from which other trees may be formed. The polypes (hydra) and the sea-anemones (actinia) multiply in this manner ; some worms are propa gated by a division of their body, and must therefore be arranged in the same division. This mode of generation re quires no distinction of sex, no copula tion, nor any particular organ.
Other modes of generation are accom plished inappropriate organs : the g:rms appear in a definite situation in the body, and the assistance of certain operations is required for their further develope ment. These operations constitute fecun and suppose the existence of sexual parts : which may either be sepa rate, or united in the same individual.
The office of the male sex is that of furnishing the fecundating or seminal fluid; but the manner in which that contributes to the devclopcment of the germ is not yet settled by physiologists. Some, forming their opinions from the human subject and the mammalia, where the germs are imperceptible before fe cundation, suppose that these are crest ted by the mixture of the male fluid with that which they suppose to exist in the female ; or that they pre-exist in the male semen, and that the female only furnishes them with an abode. Others consult the analogy of the other classes of animals and of plants. In several instances, par ticularly in the frog, the germ may be clearly recognised in the ovum, before fecundation : its pre-existence may be concluded, in other eases, from the man ner in which it is connected to the ovum when it first becomes visible ; for it is agreed off all sides, that the ovum exists in the female before fecundation, since virgin hens lay eggs, &c. From such considerations these physiologists con clude, that the germ pre-exists in all fe males, and that the fecundating liquor is a stimulus, which bestows on it an in dependent life, by awakening it, in a manner, from the species of lethargy in which it would otherwise have constantly remained.