FAT TISSUE. 55 



length becomes so large as to occupy nearly the 

 whole of the cell, leaving only a thin crescent of 

 protoplasm and a squeezed and distorted nucleus 

 crowded up against the cell-membrane. At last we 

 can no longer see, without special modes of prepara- 

 tion, any trace of cell protoplasm although a small 

 amount of this really persists as a thin shell within 

 the membrane and only the deformed remnant of 

 the nucleus. This process is called fatty infiltration. 



In those parts of the body where the fat is invari- 

 ably found, this change in the cells occurs in the 

 vicinity of little tufts of capillary blood-vessels, so 

 that at one period the forming fat is seen lying in 

 scattered clusters in the meshes of distinct groups 

 of blood-capillaries. It is these clusters of fat-cells, 

 with their accompanying blood-vessels, which deter- 

 mine, when the fat is fully formed, the lobular char- 

 acter of this tissue. 



In many parts of the body and under varying 

 conditions sometimes physiological, sometimes 

 pathological there is an accumulation of fat in 

 the protoplasm of cells ; but it is, under normal 

 conditions, for the most part temporary, and the 

 fat-cells have no definite grouping in lobules and 

 about the blood-vessels in the way above described 

 for the permanent fat. 



TECHNIQUE. 



Developing Fat from Young Animals. To study this in 

 its early stages, some of the fresh mucous tissue from the 



