FATTY TISSUE. 533 



solid kinds of fats, there are glycerides of other fatty acids (see Chapter 

 V). In all animal fats there are besides these, as FR. HOFMANN x has 

 shown, also free, non-volatile tatty acids, although in very small amounts. 



Human fat is relatively rich in olein, the quantity in the subcutaneous 

 fatty tissue being 70-80 per cent or more. 2 In new-born infants it is 

 poorer in oleic acid than in adults (KNOPFELMACHER, SIEGERT, JAECKLE) ; 

 the quantity of olein increases until the end of the first year, when it is 

 about the same as in adults. The composition of the fat in man as well 

 as in different individuals of the same species of animals is rather variable, 

 a fact which is probably dependent upon the food. According to the 

 researches of HENRIQUES and HANSEN the fat of the subcutaneous fatty 

 tissue is richer in olein than that of the internal organs; this has also been 

 observed by LEICK and WINKLER. S In animals with a thick subcutaneous 

 fat deposit the outer layers, according to HENRIQUES and HANSEN, are 

 richer in olein than the inner layers. The fat of cold-blooded animals 

 is especially rich in olein. The fat of domestic animals has, according 

 to AMTHOR and ZINK, a less oily consistency and a lower iodine and 

 acetyl equivalent than the corresponding fat of wild animals. Under 

 pathological conditions the fat may have a markedly pronounced varia- 

 tion. The fat of lipoma seems, from JAECKLE'S experience, to be poorer 

 in lecithin than other fats. 



The properties of fats in general, and the three most important varieties 

 of fat in particular, have already been considered in a previous chapter, 

 hence the formation of the adipose tissue is of chief interest at this time. 



The formation of fat in the organism may occur in various ways. The 

 fat of the animal body may consist partly of fat absorbed from the food 

 and deposited in the tissues, and partly of fat formed in the organism 

 from other bodies, such as proteins (?) or carbohydrates. 



That the fat from the food which is absorbed in the intestinal canal 

 may be retained by the tissues has been shown in several ways. RAD- 

 ZIEJEWSKI, LEBEDEFF, and MUNK have fed dogs with various fats, such 

 as linseed -oil, mutton-tallow, and rape-seed-oil, and have afterward 

 found the administered fat in the tissues. HOFMANN starved dogs 

 until they appeared to have lost their fat and then fed them upon large 

 quantities of fat and only little proteins. When the animals were killed 

 he found so large a quantity of fat that it could not have been formed 

 from the administered proteins alone, but the greater part must have 



1 Lud wig-Festschrift, 1874, Leipzig. 



2 See Jaeckle, Zeitschr. f. physiol. Chem., 36 (literature). 



3 Knopfelmacher, Jahrbuch f. Kinderheilkunde (N. F.), 43 (older literature); 

 Siegert, Hofmeister's Beitrage, 1; Jaeckle, Zeitschr. f. physiol. Chem., 36 (literature); 

 Henriques and Hansen, Skand. Arch. f. Physiol., 11; Leick and Winkler, Arch. f. Path, 

 u. Pharm., 48. 



