276 PHYSIOLOGY AT THE FARM. 



Carbon. Nitrogen. Saline matter. 



And he has given off in Grains. Grains. Grains. 



respiration, . . 2625 



Leaving, to be rejected sooner 



or later by the excretions, 885 201 253 



" In this supposed case, therefore, the carbon, nitrogen, and 

 saline matter were to each other nearly as the numbers 



Carbon. Nitrogen. Saline matter. 



35 2 2| in the food ; 



and as 



9 2 2^ in the excretions ; 



or, in other words, the carbon being in great part sifted out of 

 the food by the lungs, the excretions are necessarily much 

 richer in nitrogen and saline matter, weight for weight, than 

 the mixed vegetable and animal matters on which the man 

 has lived. 



"But the immediate and most sensible action of animal 

 and vegetable substances as manures depends upon the pro- 

 portion of nitrogen and saline matters they contain. This 

 proportion, then, being greater in the excretions than in the 

 crude vegetables, the cause of the higher estimation in which 

 the former are held by the practical farmer is sufficiently 

 clear."* 



Reproduction. The ovaries in the female, the testes in the 

 male, are the essential organs of reproduction throughout the 

 greater part of the animal kingdom. Even in plants analogous 

 organs are concerned in the same great function. In phanero- 

 gamous plants the pollen derived from the anther or male 

 organ is conveyed to the ovule at the base of the pistil or 

 female organ. It is well ascertained that no ovule becomes a 

 productive seed unless the pollen has had access thereto. The 

 same is the type of the reproductive process in animals. In but 

 few species are there not both male and female organs. In some 

 * Johnston, 'Agricultural Chemistry,' pp. 692, 693. 



