GENERAL PRINCIPLES OF BREEDING. 205 



in the emission of the semen into the uterus of the female, where 

 (or near which organ) it reaches and fertilises the ovum of the 

 female. The essence or precise nature of the semen is not known, 

 but it is not fruitful unless it contains what are called spermatozoa, 

 which are capable of moving themselves, and were formerly 

 supposed to be animalcules. These are now considered to be no 

 more than automatic particles, like those formed in the pollen 

 of some species of plants, which often show a great degree of 

 activity after leaving the parent flower ; they seem to be intended 

 to convey the essential particles or c sperm cells ' of the semen to 

 that part of the uterine system of the female where their presence 

 is required. 



2nd. The share of the female is greater than that of the male, 

 because she not only furnishes the ' germ-cell,' which is a part 

 of the ovum, analogous to the e sperm-cell ' of the semen, but she 

 also supplies them both with the materials' necessary for their 

 development, till they are able to support a separate existence. 

 The ' germ-cell ' and the yolk, together make up the ovum, which 

 is formed by the ovarium, and carried off by the oviduct just as 

 the semen is secreted by the testes, and carried off by the vas 

 deferens. 



Srdly. The 4 sperm-cell,' being furnished by the male, and the 

 ' germ-cell ' by the female, must be brought into contact before 

 the latter is fertilized, and a perfect embryo formed. As soon 

 as this contact has been established, the ( sperm-cell ' becomes 

 absorbed into the ' germ-cell,' and a tendency to increase in size 

 is set on foot and kept up by means of the nutriment contained 



