ANATOMY OF SEROUS MEMBRANES. 151 



form of cords and lobules resembles the structures above 

 described, in its anatomical structure, so far as regards its 

 superficial endothelium, plasmatic canals, blood- and 

 lymph-vessels. We perfectly agree Avith the statements of 

 Flemming in regard to the development and significance of 

 adipose tissue, and will here only repeat that fat-cells are 

 branched cells (plasmatic canal-cells) containing one or more 

 oil drops. 



Before speaking of the pathological aspects of these tissues 

 we wish to describe a structure which throws much light 

 on the evolution of adipose tissue. 



Near the glandula infraorbitalis of young rabbits is found 

 a gelatinous body, which is separated from the eye and its 

 surrounding fat by a thin membrane, rests upon a large venous 

 plexus, and is immediately behind the maxillary bone. It 

 has a smooth polished appearance precisely like that of a 

 serous membrane. 



If the skin and fascia are divided in the living animal, and a 

 small piece of this gelatinous body removed and examined in 

 fresh serum, it shows in addition to sinuous bundles of connec- 

 tive tissue, a large number of cellular structures. There are 

 beside amoeboid cells, spindle-shaped structures of various 

 size. Some are pale and have a pale oblong nucleus, others 

 extremely long, coarsely granular, with a swelling in the 

 centre or sometimes near one of the tapering ends. These 

 tapering ends may be clearly seen with a very high power 

 (No. 10 immersion of Hartnack), to run out into a simple or 

 divided bundle of the finest fibrillse, which may be traced, 

 gradually diminishing in size, to the similar process of an 

 adjacent cell. Another preparation shows, on the contrary, 

 an entirely different a^jpearance. Here only dim outlines 

 of flat structures can be traced in the hyaline substance. 

 After a short time, sometimes immediately the cover glass is 

 put on, these plates are seen to have a distinctly fibrillar 

 structure. A more or less distinct nucleus is seen in the 

 centre surrounded by a narrow belt of finely granular sub- 

 stance, and outside of this are the closely set fibril! ae which 

 run in curved lines through the plate and pass into, that is, 

 form the processes. Granules occur between the fibrils. 

 These plates vary much in size as well as in the width of 

 their processes. Now a simple manipulation shows that the 

 spindle-cells above mentioned (Avhich are precisely similar to 

 those which have been often described from embryonic con- 

 nective tissue), are only the structures of the second prepara- 

 tion seen in profile. It is only necessary to take a preparation 

 contained in a somewhat large quantity of serum and move 



