302 Transactions of the Society. 



number of fat-globules had become developed within them. In 

 this way the preparation from which Fig. 3 has been drawn was 

 made from the broad ligament of a pregnant mouse; and as an 

 example of the rapidity with which such a specimen can be made 

 by our special process, we may remark that within twenty minutes 

 after the animal had been brought to us to be destroyed, it was 

 killed by chloro'orm, opened, the membrane stretched on rings, 

 silvered and stained black, clarified, and mounted as a permanent 

 preparation. 



Strange to say, when the first modification (by injection) was 

 practised, the wandering cells were found in great numbers on the 

 tree surfaces of the membranes, as if during bleeding, injecting, and 

 cooling they had endeavoured to make their way from the blood- 

 vessels or their neighbourhood to the serous cavities ; on the con- 

 trary, when the animal was quickly killed by chloroform and 

 opened, they were seldom seen on the free surfaces. In this case, 

 the jamming of the one ring upon the other keeps the blood- 

 vessels distended by fluid blood, and the first preparation thus 

 obtained is generally faultless, yet the very act of excising the rings 

 with membrane attached opens the blood-vessels left behind, and thus 

 a thin sheet of blood-corpuscles, scarcely noticeable to the naked eye, 

 comes to be spread on the surface of the remaining membrane, and 

 when silver solution is applied, the sheet of red blood-corpuscles 

 becomes fixed in situ, and completely obscures the preparation. If, 

 however, a jet of water is directed upon this membrane before 

 applying the silver, these will all be washed away, but of course 

 leaving the various cells in an altered condition, to be fixed by the 

 subsequent apphcation of silver. This shows the great advantage 

 to be gained by using the silver on clean preparations, without pre- 

 liminary washing, as this not only washes away the cells on free 

 surfaces, but it also alters the forms of those left behind. 



Fig. o may therefore be regarded as a typical specimen of 

 wandering cells fixed in their branched condition, and in that con- 

 dition they are becoming fixed cells wherever fat is seen developing 

 witli.n them. We there see the various stages of the development 

 of fat within branched cells as clearly as they were seen within 

 round cells in Fig. 1, and the different amounts of protoplasm 

 developed round the branched wandering cells is as varied and 

 distinctive as in the round wandering cells seen in Fig. 2. In 

 short, we claim not only to have shown that fat-cells are specially 

 developed from wandering cells, but that these wandering cells 

 may appear to be round or branched cells, according to the process 

 or modifications of processes by which they have been prepared ; 

 and we believe we have thus reconciled the views of different 

 observers, as ftir as the shape of the parent-cell of the fat-cell is 

 concerned, those views being erroneous principally because they 



