AND VEGETABLE NUTRITION. 59 



of nutrition, vegetable as well as animal — in the stomach 

 and in the soil — in the lungs and in the leaves. 



The ordinary temperature of the animal stomach is 

 about 98° — air is always inhaled by the lungs, and moist- 

 ure is ever present. Hence the digestive process of 

 animals is seldom arrested from the want of these agents. 

 The decomposition of vegetable food, in the soil, ceases 

 when the thermometer falls below 40°, and is most active 

 at the temperature of 80°. Hence vegetable nutrition 

 does not go on in the winter, in the absence of heat, and 

 when most plants are shorn of their elaborating organs. 



Neither lungs nor leaves can perform their office 

 healthfully, without access to fresh air ; nor can decom- 

 position or germination take place without air. 



Water is a necessary solvent in the preparation of an- 

 imal and vegetable food, for the delicate mouths of the 

 lacteals and spongioles, and is no less indispensable as a 

 medium for transmitting the food to the lungs and leaves, 

 and from thence through the animal and vegetable struc- 

 tures. 



After the blood of the animal has been perfected in the 

 lungs, it is conducted, by minute arteries, to every part 

 of the body, and is transmuted, or converted, into flesh, 

 &c. After the sap has become elaborated or changed 

 in the leaves, it is conveyed, in like manner, to every 

 part of the vegetable system, and is transmuted, or trans- 

 formed, into wood, fruit, roots, &c. 



Vegetables, like animals, may be injured by an excess of 

 food ; and when food is too concentrated, or too rich, the 

 lacteals and the spongioles become clogged, and unfitted 

 to take up and transmit aliment to the lungs and leaves. 



A seed may be compared to an egg. One contains 

 the germ of a chick, the other, the germ of a plant. Na- 

 ture has provided in their envelopes the food proper for 

 both, in infancy, and until both are set free from their 

 envelopes, and can provide for themselves. Through 

 the agency of heat and air, the chick becomes animated, 

 grows, and bursts its shell; and the seed germinates and 

 grows, and bursts its case — its roots strike into the soil, 

 and its stem ascends above it — the roots collect food, 



