182 BOARD OF AGRICULTURE. 



power to generate adipose tissue. Where they are not absorbed, 

 accumulations of fat do not take place; and when they are 

 absorbed, without being provided with adipose tissue, they would 

 accumulate injuriously in the blood, if not drawn off by the liver. 

 Hence it is that in warm climates, where there is diminished 

 excretion through the lungs, and non-azotized food is not got rid 

 of by the respiratory process, the liver is overworked, its function 

 becomes disordered from its inability to separate from the blood 

 all that it should draw off, and these injurious substances accumu- 

 lating in the blood, "produce various symptoms that are known 

 under the general term bilious." Hence, also, some persons 

 never become fat, however large the quantity of oily matter taken 

 into the stomach ; and it is in such persons that the tendency to 

 disorder of the liver from overwork is most readily manifested ; 

 they are, therefore, obliged to abstain from the use of fat-producing 

 articles of food. It is the power, therefore, to absorb these 

 fat-producing articles of food, and to generate adipose tissue for 

 their reception, that saves the liver from being overtasked, and 

 results in accumulations of fat. The constituents of fat are termed 

 stcarine, margerine and oleine. 



We have dwelt upon the production of animal fat, and the 

 organs engaged in its manufacture, in order to show how distinct 

 a part of the animal enconomy it is, and how naturally the fat- 

 producing functions can be transmitted, independently of all 

 others, and may be cultivated at the expense of all others. 



The secretion of milk is a very different matter ; and is per- 

 formed by certain glands, whose business it is rather " to elaborate 

 from the blood certain products, which are destined for special 

 uses in the economy, than to eliminate matters whose retention in 

 the circulating current would be injurious." These glands, called 

 mammary glands, perform, as is supposed, the chief part of the 

 work of elaborating the elements of milk ; although it is not yet 

 ascertained how much of this elaboration takes place in the blood . 

 during its circulation. Be tliis as it may, the production of milk 

 is a very difierent business from the production of fat, and does 

 not result in the combination of the same elements as are contained 

 in the adipose tissue and fat-cells. 



It is well known, moreover, that the proportion of two at least 

 of the principal ingredients of milk, is liable to great variation 

 with the circumstances of the animal. Dr. Playfair has ascertained 

 "that the proportion of butter depends in part upon the quantity 



