v INTERNAL EESTITUTIVE SECRETIONS 323 



by a further synthetic reconstruction within the cytoplasm. 

 However this may be, it is certain that fat almost entirely dis- 

 appears from the blood plasma, and passes into the areolar con- 

 nective tissue (probably by means of the leucocytes), where it is 

 incorporated and stored up in the connective tissue corpuscles to 

 be utilised as the body requires it. 



The first experimental demonstration of this fact was given by 

 Fr. Hofmann (1872). He caused the whole of the fat to disappear 

 from a dog by a thirty days' fast. As the index of the complete 

 consumption of fat, he took the rapid increase of nitrogen in the 

 urine which immediately precedes death from inanition. When 

 this occurred, he began to feed the dog with much fat and little 

 meat, of which he estimated the exact protein and fat content. 

 After five days he killed the animal, and estimated the total 

 amount of fat present in the whole body, exclusive of that left 

 in the intestine. He found that in five days the animal had 

 accumulated 1353 grms. fat. Since it was impossible that the 

 whole of this fat should be derived from the few proteins ingested 

 (which would have yielded a total of 131 grms. fat), the alimentary 

 fat must be assumed to have accumulated in the tissues. 



Pettenkofer and Voit (1873) took another way of demonstrating 

 the same fact. They determined the total intake and output of 

 dogs fed copiously with fat and scantily with meat. They saw 

 that the whole of the nitrogen introduced was excreted with the 

 urine and faeces, while a large amount of the ingested carbon was 

 retained in the body. Thus the organism had accumulated a 

 large amount of a non-nitrogenous substance rich in carbon, which 

 substance could only be/at. 



Many tissues besides the adipose connective tissue are able to 

 accumulate fat. After a meal rich in fats, fat-globules of various 

 sizes are seen in the plain and striated muscle fibres, in the nerve 

 cells, gland cells, and especially in the hepatic cells. The chief 

 storehouse of fat is certainly the adipose connective tissue which 

 forms the panniculus adiposus beneath the skin, and covers or 

 fills the spaces in many internal organs, in a variable amount and 

 form adapted to the different localities. It should be noted that 

 adipose tissue is more variable in volume than any of the other 

 tissues, that it increases or diminishes in a comparatively short 

 time, according as the individual takes an excess or insufficient 

 amount of food. The fattening of stock is due principally to 

 abundant diet, and to limited muscular work. 



In examining a lobule of subcutaneous adipose tissue, under 

 the microscope, with a low power, it appears (as shown in Fig. 100) 

 to be a collection of round globules which are highly refractive 

 and crowded together. These stain black with osmic acid, and 

 consist of irregular lobules, united by a scanty amount of fibrillar 

 connective tissue, which follows the course of the blood-vessels. 



