ELEMENTARY FORMS. 31 



In like manner, the fat is still less a secretion of the uniting, 

 but, a proper tissue. ^ 



30. The Adipose Tissue, 



has only of late been recognized as an independent tissue, par- 

 ticularly by Gurlt, whilst formerly, misled by the appearance of 

 the fat vesicles in the cellular interspaces of the uniting tissue, 

 we were accustomed to regard the latter as the organ for the 

 secretion of the fat. But even the divided portions of fat, sur- 

 rounded by uniting tissue, have their own proper cells separated 

 from it. 



Distribution. The fat tissue appears connected together like a 

 membrane, especially in the uniting tissue under the corium, as 

 the most inferior layer of which (fat membrane, Panniculus adi- 

 posus) it is considered ; more abundant in children and women 

 than in the aged and men ; in greatest quantity under the sole of 

 the foot and on the mammary gland. Less perfectly formed and 

 more collected together in masses it presents itself in the orbits, 

 and as marrow in the medullary cavities of the cylindrical bones. 

 Accumulated immoderately in all the usual places, general corpu- 

 lency results ; in separate or uncommon regions it is present, as 

 lipoma (fatty tumour). 



Structure. The fat tissue consists of cells, in which a dropping fluid, the 

 fat, is contained. The cell is, inside the body, oval and smooth, becomes 

 irregular on cooling, angular or flat. Diam. = 0*018 of a line to 0*056. Their 

 surface refracts light strongly, the edges are bright silvery white when light 

 falls upon them. The vesicle is very delicate ; in its wall an oval nucleus 

 generally appears (even two). The cell becomes smaller, and is entirely 

 soluble in acetic acid. 



Development. Fat forms and becomes consumed very quickly, 

 probably in consequence of the fat-cells being dissolved (especially 

 in dyscratic diseases and after blood-letting), and the fat taken up 

 by the lymphatics and carried into the blood. 



31. Elastic Tissue, tela elastica, 



is when of some thickness yellow ; elastic but fragile, closely 

 allied to the uniting tissue ; does riot change into Gelatin by 

 boiling (Berzelius), is insoluble in concentrated acetic acid, solu- 

 ble in dilute sulphuric acid, and is precipitated from the solution 

 by Infus. of Galls, but not by ferro-cyanide of Potassium. 



Distribution. The Elastic appears in connection with other 

 tissues, but also independently, combined as membranes and flat 

 ligaments, in 



