Development, &e., of the Fat-cell. By G. and F. E. Hoggan. 365 



previously existing exhausted fat-cells, it shows well the general 

 plan of development. These fat-cells had developed peripherally 

 along the blood-vessel a, first as a single row of cells h, h, lying 

 along or upon the vessel, and afterwards externally to that single 

 file as in the case of cells e, c and d, d. 



Tl]e branched wandering cells from which these cells had 

 originally been developed, might fairly have been considered as 

 belonging to the so called adventitia, although at the same time 

 they were only wandering cells clustering round the vessel. So 

 far, therefore, we are inclined to agree with Flemming in the 

 identity of the cells and locality he refers to, although we cannot 

 agree with him in holding that these are fixed branched cells, or 

 that the development of fat-cells only takes place in the so-called 

 adventitia, and in being too exclusive as to the locality of develop- 

 ment ; for, as seen in our drawings, fat-cells may develop either 

 singly (Figs. 1, 3), or in islands (Figs. 7, 9. and 11) unconnected 

 with any vessel whatever, although it is quite possible that the 

 parent-cells only a short time previously formed part of the so-called 

 adventitia of the nearest veins. 



It is a matter of common observation that the tracts or masses 

 of fat-cells lie close to the lines of blood-vessels, or, in other words, 

 close to the centres of nutrition, and considerable importance has 

 been attached to the question of the direction in which their develop- 

 ment proceeds. This we consider to be a wholly unnecessary 

 question, only brought forward by way of supporting certain 

 erroneous hypotheses, and we only now notice it lest our silence 

 be mistaken for acquiescence in them. 



Laying aside Toldt s idea that the fat-tracts are developed as 

 glands from special centres in the embryo, as being too extreme and 

 palpably incorrect for serious discussion, let us pass to Flemming's 

 hypothesis * that the fat-cells near blood-vessels develop first close 

 to the vessels and are then pushed to the periphery by the growth 

 of succeeding fat-cells, in other words, that development is from the 

 centre of nutrition to the periphery. This view seems to be insisted 



* Since the above was written, we have found that Flemming has recently 

 published another article on fat-cells in vol. xii. for 1876 of the ' Archiv fiir 

 Mikroskopische Aratomie.' That article seems to be in great part a defence of 

 his former opinions, which had been attacked by Klein and others. He has, 

 however, modiiied his views as to the development of fat-cells close to and from 

 tlie adventitial of blood-vessels, in somewhat the same sense as we have put it. 

 He also acknowledges that he was wrong in speaking of the whole of the proto- 

 plasma of the fot-cell outside tlie fat-globule as the cell-wall, and he corrects 

 himself so far as to speak of it only as i^rotoplasm, outside of which, however, he 

 describes in very vague terms another, or, as he calls it, a secondary cell-wall or 

 membrane not always necessarily present. In short, he has adopted Ranviers 

 idea of a fat-cell-wall, pure and simple, in which what remains of the original pro- 

 toplasm is still to be seen on its internal surface, only he des^iibes it differently 

 as a secondary membrane f >rmed outside of the protoplasm, a condition even more 

 complicated and more imtcnable than his former opinion. 



