370 GENERAL VIEW OF THE HUMAN FUNCTIONS. 



dom accurately made, and a very confused notion on the subject is generally 

 prevalent. 1 



387. The process of Reproduction, like that of Nutrition, has been until re- 

 cently involved in great obscurity; and although it cannot be said to be yet 

 fully elucidated, it has been brought, by late investigations, far more within our 

 comprehension than WAS formerly deemed possible. The close connection be- 

 tween the Reproductive and Nutritive operations, both as regards their respec- 

 tive characters, and their dependence upon one another, has long been recog- 

 nized j and it is-now rendered still more evident. Nutrition has not been unaptly 

 designated "a perpetual reproduction;" and the expression is strictly correct. 

 In the fully-formed organism, the supply of alimentary material to every part 

 of the fabric enables it to produce a tissue resembling itself; thus we ordinarily 

 find true bone produced only in continuity with bone, nerve with nerve, muscle 

 with muscle, and so on. Hence it would appear that, when a portion of tissue 

 has once taken on a particular kind of action, it continues to reproduce itself on 

 the same plan. But in the developmental process it is different. A single cell 

 is generated by certain preliminary actions, from which cell, all those which 

 subsequently compose the embryonic structures, take their origin; and it is not 

 until a later period, that any distinction of parts can be traced, in the mass of 

 vesicles which spring from it. This distinction becomes more and more obvious 

 as development advances; the form and position of the principal organs being 

 first marked out by peculiar aggregations of cells; and the intimate structure of 

 each being gradually brought to the type which is characteristic of it. Hence 

 we may state the essential character of the function of Reproduction to consist 

 in the production of a cell of most peculiar endowments; which, when supplied 

 with nutriment, and acted on by warmth, does not simply multiply itself so as 

 to produce a mere aggregation of similar cells, but gives origin to a succession 

 of broods, which undergo such heterogeneous transformations, as ultimately to 

 evolve an organism capable of maintaining an independent existence, in which 

 the number of different parts is equal to that of the functions to be performed, 

 each separate part having an office distinct from that of the rest, and being 

 specially adapted to it alone. 



388. But, it will be inquired, how and where in the Human body (and in the 

 higher Animals in general) is this embryonic vesicle produced, and what are 

 the relative offices of the two sexes in its formation? This is a question which 

 must still be answered with some degree of doubt; and yet observed phenomena, 

 if explained by the aid of analogy, seem to lead to a very direct conclusion. 

 The embryonic vesicle itself, like other cells, must arise from a germ; and 

 reasons will be hereafter given for the belief, that this germ is the product of 

 the admixture of the contents of the " sperm-cell" of the male with that of the 

 "germ-cell" of the female; and that this admixture is requisite for the regenera- 

 tion of that " germinal capacity" which is gradually expended in the develop- 

 mental process. The operations immediately concerned in this function, as in 

 that of Nutrition namely, the preparation of the " sperm-cells" and the " germ- 

 cells," the act of fecundation, and the development of the ovum are not depend- 

 ent upon nervous agency, and are but little influenced by it ; and the functions 

 of Animal Life are called into play only in the preliminary and concluding steps 

 of the process. In many of the lower Animals, there is no sexual congress, 

 even where the concurrent action of two sets of organs, belonging to two sepa- 



1 It has been commonly said, for example, that the function of Respiration is the con- 

 necting link between the two : the fact being, however, that the true process of Respira- 

 tion is no more a function of Animal life than is any ordinary process of secretion; but 

 that, in order to secure the constant interchange of air, which is necessary to its perform- 

 ance, the assistance of the nervous and muscular systems is called in, though not in a man- 

 ner which necessarily involve.-; either consciousness or will. 



