Development, &c., of the Fat-cell. By G. and F. E. Iloggan. 377 



by journeying as wandering cells. That they have this property, 

 we think we can demonstrate satisfactorily by means of specimens 

 which we show to-night. 



If, in the first place, we start with cell a, Fig. 1 0, which seems 

 to have left the group of fat-cells shown there, we can pass on to 

 another example, Fig. 16, where four of such granular cells can be 

 seen lying within a natural hole of a membrane, like cell h, Fig. 1, 

 and lying, moreover, within a group of wandering cells for w^hich 

 they cannot possibly be mistaken ; for the large oval contour filled 

 with granules, a nucleus sharply defined and of a reddish colour 

 (when stained by pyrogallate) contrasts strongly with the blue- 

 black polynuclear condition of the wandering cells surrounding 

 them. 



Only one link is missing, and that also we supply, by showing 

 in a, Fig. 15, such granular cells in the branched condition, moving 

 along by the side of blood-vessels, and contrasting strongly with 

 the transparent delicate branched cells 6, h, near them. 



It would, therefore, appear that when from a fat-cell all the fat 

 has become absorbed and it has passed into granular retrogression, 

 the faculty of locomotion is restored to it, that indeed it is in 

 the condition of a wandering cell, plus the granules which it con- 

 tained. But it would further appear that, while wandering and 

 while its own granules are moving off from it, a supply of nutrition 

 checks the granular exodus without checking the cell wandering (or 

 exodus as regards the fat- tract), and then the granules may cluster 

 round the nucleus in every possible form of irregularity, looking 

 like the peripheral crystals in a lump of sugar. Gradually, however, 

 these granules seem to melt into the substance of the cell, and it is 

 again finally seen as a round or oval flat cell with sharp border and 

 granular contents, which gradually become less granular, until the 

 granular cell, the quondam fat-cell, becomes indistinguishable in 

 appearance from any other wandering cells and, as we already have 

 seen from its presence in the natural hole of a membrane and 

 therefore on its free surface, it has also the same nomadic faculty, 

 and indeed with that faculty we see no reason why it should not 

 be discovered within blood-vessels where we have not yet looked 

 for it. The time taken to efi'ect all these changes is comparatively 

 long, and we have not yet been able to fix a limit. We believe 

 that a fortnight is not sufiicient, and this fact is apt, as we have 

 already noted, to introduce a complication into the study of this 

 question ; for just as it seems the rule that a mouse may be reduced 

 often to the point of starvation while at large, the vestiges of such 

 granular cells are sca'jely ever entirely absent from some prepa- 

 ration, although we are able to show two or three in which they 

 have not been found to exist. When, moreover, we take into con- 

 sideration the fact that other cells beside fat-cells have the power 



