414 E. T. Bell. 



became prominent in the seventies. One of these views, first clearly 

 formulated and developed by Flemming (8, 9, 10, 11, 12), is that 

 adipose tissue is only fibrillar connective tissue in which the cells 

 have become filled with fat. Adipose tissue is not a special kind of 

 tissue. Czajewicz (G) and Virchow had come to conclusions similar 

 to this before the appearance of Flemming's work. Jakowski (17) 

 agreed with this conception. These investigators gave almost no 

 attention to the primitive fat organs.^ 



The other theory advanced by Toldt, is that adipose tissue is a 

 special kind of tissue. It develops from sj^ecial organs (Toldt's 

 Fettkeimlager, Kolliker's Priraitivorgane der Fettlappchen). All 

 the adipose tissue of the body is formed by outgrowths of these primi- 

 tive organs. This was the view of Ranvier (29), Klein (20), Bob- 

 ritzky (3 a), Metzner (23), Altmann (1) and others.^ Essentially 

 the same view was held by Lowe (22). 



Waideyer's view (38) is a compromise between Flemming and 

 Toldt. He states that fat cells develop both from special cells (those 

 of the primitive organs) and ordinary connective tissue cells. He also 

 states that wandering cells may enter a fat lobule and become fat 

 cells. Lowe also assigns an important role to the wandering cells 

 in the formation of fat cells. Gage (13 a) held that fat cells develop 

 mainly from ordinary connective tissue cells, but that wandering 

 cells may also become fat cells. 



Kolliker (21) took the position that the fat cells are all derived 

 from connective tissue cells. Some cells begin to accumulate fat as 

 ordinary branched connective tissue cells; others (those of the primi- 



^Flemming gave a little attention to the primitive organs in his last paper. 



"Toldt (35) in a later discussion admits that many fat cells are devel- 

 oped not from the primitive organs but from connective-tissue cells. But he 

 does not regard these connective-tissue fat cells as true fat cells. He seems 

 to think that they are analogous to cells like those of the liver, which may 

 accumulate fat but which are not regarded as true fat cells. As an argu- 

 ment for this contention that the cells of the primitive organs are not con- 

 nective-tissue cells he points out that the cells of the primitive organs do 

 not revert to a branched condition when deprived of their fat as do the 

 cells of ordinary connec-tive tissue. Toldt did not study the type of fat orgau 

 found in the calf foetus. 



