2/J.8 Human Physiology. 



germs or eggs formed in the ovaries of the female, which at a 

 certain stage of development are impregnated, or fecundated, 

 by union with a similar germ, produced in a somewhat similar 

 organ of the male the male and female elements uniting to 

 produce the perfect being. The unfertilised, unimpregnated, 

 or unfecundated ovum or egg quickly perishes. The one to 

 which has been added the masculine element is from that 

 moment endowed with life, and, with favouring conditions, 

 developes with a wonderful rapidity. 



Fishes produce a vast number of eggs, as may be seen in the 

 hard roe of herring, which, when they have arrived at a certain 

 stage, are spawned that is, expelled from the body in places 

 which the fish instinctively find for that purpose. Salmon come 

 hundreds, perhaps thousands of miles through the deep ocean 

 to lay their eggs in the shallow fresh water streams in which 

 they themselves were hatched. The male herring and salmon 

 produce, in organs not unlike the ovaries, myriads of sperm 

 cells, destined to fertilise the germ cells of the female. This is 

 the soft roe a brain-like substance, chiefly composed of these 

 cells. The male fishes attend the females, and fill the water 

 where their eggs are laid with what seems a milky fluid. The 

 two elements come into contact, perhaps by a mutual attraction, 

 fecundation takes place, and, in due time, swarms of young 

 fishes are the result. 



With insects and birds, the process is a little varied. The 

 eggs are formed, as with the fishes, in the ovaries of the females, 

 but at a certain stage they are fecundated before leaving the 

 body, by the male element being conveyed to them by a 

 process similar to that which takes place in flowers. The 

 seminal fluid of the male, corresponding to the pollen of the 

 plant, is conveyed to the germ in the ovary by means 

 specially adapted to that purpose. After the egg has 

 grown to its full size in insects covered with a tough mem- 

 brane, and in birds with a hard shell it is nlaced in som 



