354 Transactions of the Society. 



amongst observers, we might certainly suppose that the fat-cell was 

 that element. 



Instead of this unanimity, however, we find the most opposite 

 opinions held at the present day as to its origin alone, while about 

 its disappearance, so far as we can discover, nothing really definite 

 is known. We therefore propose in this paper to trace the life- 

 history of the fat-cell from its origin in the wandering cell, its 

 development, its decline, and its final disappearance from the stage 

 under the same form in which it made its first appearance there. 



food was given, and the animal killed twenty hours afterwards. Tissue treated 

 ■with silver, osmic acid, and logwood solutions, b, c, d. Cells in which many- 

 globules of fat have been deposited rapidly. These cells were probably previously 

 fot-cells from -which the fat had been absorbed, as seen in Figs. 9 and 10. 

 /■, q. Cells from which fat had not only been absorbed, but whose protoplasm had 

 been disintegrating by granular exodus, as seen in Figs. 10, 12, and 13. The 

 return of nutriment sent the granules back to the cell, where they now 

 stain so intensely as in most cases to hide the nucleus. In g the nucleus is 

 visible, and although stained as deeply as the nuclei of the neighbouring cells, it 

 appears almost colourless as compared with the intense blue of the clustering 

 granules round it. a. Vein, h, h. Nuclei of the endothelium. 



Fig. 6. — Margin of a group of fully developed fat-cells, as they are generally 

 seen, from the mesentery of a guinea-pig, treated with silver and logwood solu- 

 tions and mounted in varnish, showing the effect of compression in making them 

 assume a polyhedral shape, a, a. Fat-cells whose free borders still retain the 

 circular form. 6, h. Fat-cells assuming tlie polyhedral form through pressure of 

 neighbouring fat-cells. This is the form in which they are found in nine cases 

 out of ten. 



Fig. 7. — Fat becoming absorbed from fat-cells. From the omentum of a 

 young man who died of cancer and much emaciated. More than one-half of the 

 contained fat has been absorbed from the cells. 



Fig. 8. — Fat-absorption in a further advanced stage than Fig. 7, from the 

 subcutaneous tissue of a young man who died of Eastern leprosy, much emaciated. 

 Tissue treated with osmic acid and picro-carinine. Some of these cells still retain 

 the angular form they possessed when fully distended with fat and compressed 

 by neighbouring fat-cells. 



Plate XIV. 



Fig. 9. — Still further advanced stage of fat-absorption, from the broad liga- 

 ment of a pregnant mouse, found almost dead from starvation. In this specimen 

 the first stage of retrogression — that of fat-absorption — is seen completed, a, a. 

 Monoglobular fat-cells, once fully distended, by fat now undergoing absorption. 

 b, b. Multiglobular fat-cells undergoing fat-absorption in tire multighjbnlar con- 

 dition, c, c. Fat-cells from which all the fat has been absorbed, d, d. Nuclei of 

 the surface endothelium, e, e. Edge of dense tract of exhausted fat-cells lying 

 along lines of great blood-vessels. /. Capillary blood-vessel. No difference is 

 traceable between the fat-cells in man and those of the smaller mammals. 



Fig. 10. — From the same preparation as Fig. 9, showing the commencement of 

 the second stage in retrogression of the fat-cell, when the cell-substance breaks up 

 and moves off in the form of granules, h. Group^^of exhausted fat-cells from which 

 all the fat has become absorbed, a. General b1-eak up of one of the cells of the 

 group ; the granules are seen passing away from it in every possible direction. 

 6, c. Similar cells, in which the break-up is even further advanced. /. Spindle- 

 shaped cell belonging to a capillary now broken up. A. Nuclei of surface 

 endothelium. 



Fig. 11. — From the same animal as Fig. 5, where fat has been deposited 

 in cells similar to those seen in group h. Fig. 10. These cells had undergone 

 granular change but not exodus, so that the newly formed fat-globules appear 



