688 OF REPRODUCTION. 



may be employed in generating new individuals ; since, when the body is 

 divided into numerous parts, each one of these has the power of developing 

 all the rest of the structure, and thus of becoming a complete animal ( 9). 

 Still we find in most Plants, and in all Animals, some portion of the structure 

 specially designed to form and to set free germs, which are destined to become 

 new individuals; and it is in the liberation and development of these, that the 

 function of Reproduction essentially consists. 



899. In Plants it is very evident that these germs differ but little from 

 those which elsewhere produce new cells ( 122) ; and that the first aspect 

 of the new being is neither more nor less than a single cell, in which all the 

 other cells of the structure subsequently originate. In the Cryptogamia, the 

 cell-germs are contained in what is termed the spore; and, when liberated 

 from the parent, they are developed into cells without any further assistance 

 than that which they derive from the air, moisture, &c., that surround them. 

 In Flowering Plants, on the other hand, the cell-germs are conveyed into a 

 new set of organs, in which they are supplied with nutriment previously ela- 

 borated for them by the parent ; and, in this manner, they are enabled to attain 

 an ultimate development which is much higher than that of the Cryptogamia. 

 It is now well established, that the pollen-grain of Phanerogamia is analogous 

 to the spore of Cryptogamia; since it contains the reproductive granules, which 

 are the germs of the first cells of the new individual. When the pollen-grains 

 are cast upon the stigmatic surface, they project one or more long tubes, which 

 insinuate themselves down the soft loose tissue of the style, and reach the 

 ovarium. Into these tubes, the granules which the pollen-grain contained are 

 seen to pass; and they are thus conveyed into the ovules, the foramina of 

 which are penetrated by the extremities of the pollen-tubes. The ovules 

 previously contained nothing but starchy matter; but from the time that the 

 pollen-tubes have thus implanted (as it were) their contents in their cavity, 

 they may be considered as fecundated. The subsequent growth of the embryo 

 from the first-formed cells, takes place according to the principles already 

 stated, under the head of Nutrition ; and thus it is seen, that the mysterious 

 process of Reproduction evidently consists, in Flowering Plants, of nothing 

 else than the implantation of a cell-germ prepared by the mule organs, in a 

 nidus or receptacle adapted to aid its early development, which nidus consti- 

 tutes the essential part of the female system. 



900. There is now good reason to believe that, in no Animals, is the Re- 

 productive apparatus less simple than it is in the higher Plants ; that is to 

 say, in every instance, two sets of organs, a germ-preparing, and a germ- 

 nourishing, are present. These organs differ much in form and complexity 

 of structure in the various tribes of Animals ; but. their essential function is 

 the same in all. Those which are termed Male organs prepare and set free 

 certain bodies, which, having an inherent power of motion, have been sup- 

 posed to be independent Animalcules, and have been termed Spermatozoa ; 

 there is but little reason, however, to regard them in this light, since ciliated 

 epithelium-cells may exhibit as much activity ; and there is no evidence that 

 their function is any higher than that of the pollen-tube of Plants, which con- 

 veys into the ovulum the germs of the first cells of the embryo. This view of 

 the character of the Spermatozoa rests alike upon the nature of their move- 

 ments, and the mode of their production.* Dr. Barry's observations on the 

 history of the Ovum, and on the nature of the act of Fecundation (which will 

 be presently given in some detail) have left scarcely any doubt, that this act 

 consists in the introduction of some new element into the Ovule, through the 

 medium of the Spermatozoa ; the arrival of which at the surface of the ovary 



* See Principles of General and Comparative Physiology, GOG. 



