APPENDIX. 539 



u This hiatus in the structural history of that peculiar 

 animal tissue, fat, the present brief remarks are intended in 

 some measure to fill up. 



" When the little fatty masses which are met with so abun- 

 dantly in the neck, in the neighbourhood of the thyroid and 

 thymus glands, as also in some other situations in a foetus 

 nearly or quite arrived at maturity, are examined, it will be 

 observed, by the use of a lens only, that these masses are 

 each composed of a number of distinct and opaque bodies of 

 various sizes, presenting a smooth outline, having a more or 

 less rounded or oval form, and held loosely together by fibro- 

 cellular tissue, the extension of which forms the envelope 

 which invests each of these bodies. It will also be further 

 noticed, that each mass of fat is supplied with one or more 

 blood-vessels, and that these break up into numerous lesser 

 branches, one of which goes to each of the previously-de- 

 scribed bodies, being conveyed to it by the connecting fibrous 

 tissue ; and that, having reached this body, it undergoes a 

 further subdivision, the branches extending over its entire 

 surface. 



" In continuation of these observations, it will be remarked, 

 that each of these peculiar bodies bears a close resemblance, 

 in its general aspect, to a lobe of a sebaceous gland a 

 resemblance, which, as will be seen almost immediately, ex- 

 tends even to its internal structure. 



" If a number of these bodies be torn into fragments with fine 

 needles, and be examined with a half or quarter-inch object- 

 glass, it will be observed that the cavities of some of them are 

 filled with cells of a large size, and which again are occupied 

 with numerous globules of various dimensions, presenting many 

 of the characters of oil globules, but being of greater consist- 

 ence. (Plate LXIX.^. 10.) These cells, save by their some- 

 what larger size, it is impossible to distinguish from the perfect 

 cells of sebaceous glands ; so complete indeed is this resem- 

 blance, that at first sight I did not hesitate to regard them as 

 belonging to some sebaceous gland, and which I was much 

 astonished to encounter in such a situation. Others of these 

 peculiar bodies, which may be termed ( fat cysts,' contain a 



u u 



