378 Transactions of the Societij. 



or fate to become granular, and, moreover, that other processes 

 besides starvation will reduce even the fat- cell into the granular 

 condition, we may form a fair idea of the difficulties surrounding 

 this research and the liability to errors which it possesses. 



Apart from the question of disease, if a tame rat be put into 

 a cage with some strangers, these latter, if they are powerful 

 enough, will often so maltreat the new-comer as to reduce it to a 

 skeleton, or even kill it outright, and then the same phenomena 

 of fat-cell absorption may be witnessed. Although young rats 

 while they are being suckled are generally plump and fat, they 

 rapidly become lean when weaned and forced to provide for 

 themselves instead of being dependent on the mother's milk. In 

 such cases, even although food had been continuously supplied, we 

 have found the fat-cells exhausted and granular cells abundant, 

 which could only be accounted for by the change in nutrition 

 subsequent to weaning. Even more interesting is the condition of 

 the fat-cells during excessive lactation, and the bearing which this 

 has upon the same condition in the human female. In rats and mice, 

 pregnancy is accomimnied by a great accumulation of fat in the tracts 

 near the blood-vessels, as if in preparation for the demands about to 

 be made upon the mother by her nurslings. A short time ago a 

 female mouse, having been trapped, was brought to us to be 

 destroyed, and we afterwards noticed that it was extremely lean, 

 and that its teats were pendent and flaccid, as if it were nourishing 

 a large litter of well-grown young ones, which we afterwards proved 

 to be a fact. From this animal's broad ligament and mesentery 

 specimens were prepared which showed all the stages of retro- 

 gression, similar to those seen in Figs. 9, 10, and 13, although, 

 from the immense number of exhausted fat-cells near the lines of 

 blood-vessels, it was evident that, shortly before, the animal had been 

 extremely fat, but it had been brought down to a condition identical 

 with that found in starvation, by the excessive demands of its young 

 upon it. We have thought it unnecessary here to enter upon any 

 speculation as to the channels by which the granules of protoplasm 

 move off from their parent-cell ; by the aid of the binocular Micro- 

 scope and one preparation whose endothelium is marked by silver 

 on both surfaces, it is easy to decide that the granules are moving 

 oflf through the soft gelatinous matrix which forms the membrane. 

 They move off in every direction and by no definite channel, and 

 lest some one should invoke the presence of lymphatic radicles as a 

 channel of exodus, we can only say that, after having made a 

 speciality of the search for lymphatic radicles or vasa seiosa, such 

 channels are purely mythical, and have no foundation in fact. 

 They may j)ossibly pass away finally by the blood-vessels or 

 lymphatics, or even more probably they may be absorbed or appro- 

 priated by the wandering cells, and we can from this easily imagine 



