Development, &c., of the Fat-cell. By G. and F. E. Eoggan. 373 



by mechanical pressure, and where the vitellus is seen pouring 

 out through the rent in the viteUine envelope. On the contrary, 

 there is clearly no membrane here to rupture, and the granules 

 appear to emerge from every point of the surface of the mother- 

 cell ; and we here desire to state that each of the departing granules 

 has been drawn in situ by the aid of the camera lucida, and that 

 we have in no way drawn upon our imagination in depicting this 

 phenomenon. In Fig. 10 it will also be observed that there are 

 stages in the granular exodus ; ceU h, for example, has retrograded 

 further than cell a, and cell c further than cell h ; or, in other 

 words, the granular exodus has been going on longer, and a greater 

 number of granules have left cells c and h than cell a, but the 

 continuous change onwards in absorption can be better studied in 

 Fig. 13, from the same animal and preparation as Figs. 9 and 10. 

 In this Plate we are brought to what may be considered as the last 

 chapter in the life-history of the fe,t-cell. In it the least advanced 

 in retrogression are cells a, a, still undergoing the granular exodus. 

 Cell 1), however, has almost reached the last stage of this process, 

 and in it a definite outline is again appearing, and the nucleus is 

 again becoming distinct, being no longer hidden by the swarm 

 of granules clustering round it, as in the case of the less advanced 

 cells. Beyond cell h we have a group of cells e, which have 

 probably belonged to a group of fat-cells similar to that seen in 

 Fig. 10. From them the granules have almost entirely departed, 

 leaving them in the condition of branched wandering cells, similar 

 to those seen in Fig. 3, the faintly tinted protoplasm in both cases 

 being almost destitute of granules, and visible apparently more in 

 consequence of difference of refraction between them and the 

 gelatinous matrix in which they lie than by any distinct colour or 

 tint. 



In fact, we have now come upon debatable ground, where there 

 is room for discussing whether such branched cells are really the 

 offspring or result of the granular exodus from fat-cells or hon^ fide 

 wandering cells. 



A certain number of granules can still be detected here and 

 there within their protoplasm, but it is difficult to say whether 

 these are a residuum of the original fat-cell or eaten as pabulum by 

 the wandering cell. By long and careful examination, we have 

 come to the conclusion that those cells c, c, are the remains of the 

 fat-cells which we have thus traced ba<jk to their original condition, 

 but we have considered it advisable to place the contras as well as 

 the pros of the question before our readers. 



It ought also to be borne in mind that other cells besides these 

 contain granules, and that granular exodus is not confined to fat- 

 cells, which are shown here as typical of a condition, and not as 

 undergoing a change special to themselves. The blood capillaries 



