54 NORMAL HISTOLOGY. 



protoplasm of the cells is replaced by fat, which 

 crowds the remaining part, together with the nucleus, 

 to the side of the cell, nearly or entirely concealing 

 both. The fat-cells thus formed are arranged in 

 clusters or lobules, enclosed by fibrillar connective 

 tissue, which sends into the lobules and between the 

 cells broader and narrower bundles, which serve to 

 support the cells and carry the blood- and lymphatic- 

 vessels, etc. Owing to the pressure to which the 

 fat-cells are subjected, they usually assume, in the 

 adult animal, a polyhedral form. 



Sometimes the fat appears within the cell in the 

 form of clusters of radiating needle-like crystals. 



In order to understand clearly the nature of adult 

 fat-tissue, it is necessary to study it during the pro- 

 cess of development. At an early period of life, 

 those parts of the body which are finally to become 

 fat-tissue possess the character of mucous tissue 

 with a more or less fibrillated intercellular substance. 

 The first change which we notice in the cells as the 

 transformation into fat-tissue commences, is the ap- 

 pearance in the cell-body of small shining particles. 

 These particles, of which there may be many, be- 

 come gradually larger, until they present the form 

 and character of distinct droplets of fat. As these 

 droplets increase in size, they coalesce, forming one 

 or more drops, which presently become large enough 

 to crowd the nucleus to one side. The growing 

 drops finally unite into one large drop, which at 



