Development, &c., of the Fat-cell. By G. and F. E. Hoggan. 357 



Microscope we are studying physiological changes rather than special 

 anatomical elements, changes which, in the space of a few clays, may 

 pass from the first appearance of fat in a cell to its fall development, 

 and subsequent decline and disappearance. 



While the conclusions of many of the observers we have enume- 

 rated have been arrived at on the bodies of fishes, frogs, porpoises, 

 &c., we have specially drawn our conclusions from investigations 

 carried out on the smaller mammals, as bearing more directly 

 upon man, and wherever possible we have compared these with pre- 

 parations from the human body, with the result of finding complete 

 identity throughout. Contrary, however, to the opinion of many 

 authorities, we have found the serous membranes the most useful 

 for our investigation, being enabled to utilize these by virtue of special 

 methods of our own, which we shall describe. Of these membranes the 

 most serviceable is the growing broad 

 ligament of pregnant rats and mice ; for 

 the growth of this thin structure during 

 their short term of gestation is so rapid, 

 that the developing cells and other 

 structures remain isolated, having no 

 time to form themselves into the dense 

 masses which seem to have foiled other A, Upper ring ; B, Lower ring; 

 observers. Indeed, confining one's ex- C, Membraiie between them. 



aminations to sections of tissue, as 



recommended, would render it impossible to see the most interest- 

 ing of the phenomena in the life of the fat-cell, which can 

 only be recognized in uninjured membranes, and at the extremes 

 of cell promontories or isolated cell groups or islands in such 

 membranes. 



Before ever the membrane is excised from the body of the 

 animal, it must be evenly stretched once for all, so as to keep the 

 lines of vessels apart from each other, and consequently the tracts of 

 fat-cells which lie close to them clear for examination. Moreover, 

 while the various reagents are gently applied, and the membrane 

 is being continually subjected to examination under the Microscope, 

 no fold must ever ruffle its surface, nor any object be touched by 

 it until it is permanently put up as a preparation. 



These desiderata are obtained by using the histological rings 

 invented by us, of which we show specimens. They will be found 

 to be most simple and useful adjuncts in the biological laboratory. 

 These rings are always made in pairs, one fitting tightly upon the 

 other, with a certain amount of taper in each ; and when a piece of 

 membrane is jammed between them, the whole has the appearance 

 of a tambourine. They ought always to be made of vulcanite, as 

 metals are acted upon by acids ; bone, ivory, and other animal sub- 

 stances throw down salts like chloride of gold from their solutions ; 



