Microscopical Society of London. 809 



solution of carmine. The consequences were, that vessels of extreme 

 minuteness were perfectly filled with the fluid, and were thus rendered 

 visible in the most delicate tissues of the body. Upon subsequent 

 dissection the fat was found to be visibly tinged with the carmine. On 

 a minute inspection, large vessels were discovered going to the adi- 

 pose masses, which divided and subdivided, until the unassisted eye 

 could no longer follow the ramifications. For the purpose of tracing 

 their final distribution, pieces of the fat were placed upon slips of 

 glass, and after drying were immersed in turpentine, and afterwards 

 mounted in Canada balsam in the usual manner. Upon examining 

 these under the microscope, it was found that the carmine injection 

 had not only passed from the arteries into the capillaries, but had also 

 from these last entered into the veins, thus injecting both arteries and 

 veins, the latter being readily distinguished by a slight difference of 

 colour, occasioned by the presence of a small amount of blood, amply 

 sufficient to enable the anatomist to trace the two kinds of vessels 

 through all their ramifications. 



Mr. Smee divides fat into four kinds: — laminated, masses, gra- 

 nules and fat of omentum. These modifications are not occasioned 

 by any specific difference in the substance of fat itself, but solely by 

 the situation in which it is found. In all cases it is composed of 

 cells, of a round or oval form, which, when many are aggregated toge- 

 ther, in consequence of pressure assume polygonal forms, the hexagon 

 being the more usual. These cells contain the fatty material, and 

 each is invested with a membrane. Their size varies from T ±-& to 

 -g-^yg. of an inch. In laminated fat one or more vessels enter the 

 mass, which are continually divided and subdivided until the eye can 

 no longer follow the ramifications, the branches frequently anastomos- 

 ing with each other ; these branches extend to the extreme margin of 

 the layer of fat. In granular fat, the distribution of the vessels is not 

 so distinct to the naked eye; still, however small the granule may be, 

 a little twig is required to be distributed to each. In the masses of 

 fat, vessels are seen to enter at certain distances, which freely join 

 each other, and these branches also subdivide, so as to supply the en- 

 tire mass equally with blood. The fat of the omentum is, however, 

 the most curious and interesting. In this, the arteries are of great 

 size and length, the principal long trunks anastomosing by large 

 branches, and the arches so formed continually divide and subdivide, 

 until at length branches are distributed throughout the whole omen- 

 tum. These vessels again give off branches laterally, which divide 

 into the minute ramifications destined to the supply of the fat. These 

 iii 2o 



