586 OF' REPRODUCTION. 



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. In Plants it is very evident that 

 these germs differ but little from those which elsewhere produce new cells 

 ( 557) ; 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 converted into a new set of organs, in which they are sup- 

 plied with nutriment previously elaborated 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 stig- 

 matic surface, they project one or more long tubes, which insinuate themselves 

 down the soft loose tissues 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 con-s 

 sidered 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 Repro- 

 duction evidently consists, in Flowering Plants, of nothing else than the 

 implantation of a cell-germ prepared by the male organs, in a nidus or recep- 

 tacle adapted to aid its early development, which nidus constitutes the essen- 

 tial part of the female system. 



733. 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 

 movements, 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 had been more than once previously seen, and the penetration of which 

 to the ovum there was good reason to suspect ; and these have been confirmed 

 by the observations of Dr. A. Farre on the Ovum of the Earth-worm, which 



* See Principles of General and Comparative Physiology, 006. 



