5-42 SEXUAL GENERATION. 



upon itself, which opens by an external orifice (c) upon the lateral 

 border of the articulation, about midway between its two ex- 

 tremities. The spermatic fluid produced in the testicle is intro- 

 duced into the female generative passage, which opens at the same 

 spot, and, penetrating deeply into the interior, comes in contact 

 with the eggs, which are thereby fecundated and rendered fertile. 

 The fertile eggs are afterward set free by the rupture or decay of 

 the articulation, and a vast number of young are produced by their 

 development. 



In snails, also, and in some other of the lower animals, the ovaries 

 and testicles are both present in the same individual ; so that these 

 animals are sometimes said to be " hermaphrodite," or of double 

 sex. In reality, however, it appears that the male and female 

 organs do not come to maturity at the same time ; but the ovaries 

 are first developed and perform their function, after which the tes- 

 ticles come into activity in their turn. The same individual, there- 

 fore, is not both male and female at any one time; but is first 

 female and afterward male, exercising the two generative functions 

 at different ages. 



In all the higher animals, however, the two sets of generative 

 organs are located in separate individuals; and the species is 

 consequently divided into two sexes, male and female. All that 

 is absolutely requisite to constitute the two sexes is the existence 

 of testicles in the one, and of ovaries in the other. Beside these, 

 however, there are, in most instances, certain secondary or acces- 

 sory organs of generation, which assist more or less in the accom- 

 plishment of the process, and which occasion a greater difference in 

 the anatomy of the two sexes. Such are the uterus and mammary 

 glands of the female, the vesiculaa seminales and prostate gland 

 of the male. The female naturally having the immediate care of 

 the young after birth, and the male being occupied in providing 

 food and protection for both, there are also corresponding differ- 

 ences in the general structure of the body, which affect the whole 

 external appearance of the two sexes, and which even show them- 

 selves in their mental and moral, as well as in their physical 

 characteristics. In some cases this difference is so excessive that 

 the male and female would never be recognized as belonging to the 

 same species, unless they were seen in company with each other. 

 Not to mention some extreme instances of this among insects and 

 other invertebrate animals, it will be sufficient to refer to the well- 

 known examples of the cock and the hen, the lion and lioness, the 



