524 CHARACTERS OF LYMPH. [BOOK n, 



a certain number of red blood-corpuscles; sometimes these are 

 sufficient to give the lymph '(or chyle) a reddish tinge. They have 

 been observed within the living lymphatic vessels and have prob- 

 ably in some manner or other made their way from the blood into 

 the lymph channels. 



296. The chemical composition of lymph, even when taken 

 in each case from the thoracic duct, varies a good deal. The total 

 solids are much less than in blood, amounting in general to not 

 more than 5 or 6 p.c. The deficiency is in the proteids, not in 

 salts. The latter are, broadly speaking, very much as in blood ; 

 the former amount on the average to about 3 or 4 p.c., that is to 

 say, to about half as much as in blood, the particular proteids 

 present being apparently the same as in blood, viz. albumin, 

 globulin and fibrinogen. In certain cases the lymph from the 

 thoracic duct, even of a fasting animal, is very opalescent, indeed 

 may be quite turbid ; the turbidity is then found to be due, not to 

 fat, but to proteids, probably of a special kind or kinds. In lymph, 

 as distinguished from chyle, the quantity of fat is small, and 

 consists of the usual neutral fats and the soaps of their fatty acids, 

 together with lecithin ; cholesterin may also be present. A certain 

 amount of sugar (dextrose) appears to be always present, and 

 several observers have found an appreciable quantity of urea. The 

 ash of lymph like that of blood serum contains a considerable 

 quantity of sodium chloride, while phosphates and potash are 

 scanty ; it also contains iron, apparently in too great a quantity 

 to be accounted for by the few red corpuscles which may be 

 present. From lymph a certain amount of gas can be extracted, 

 consisting chiefly or almost exclusively of carbonic acid, with a 

 small quantity of nitrogen, the amount of oxygen -present being 

 exceedingly small. The importance of this we shall see when we 

 come to study respiration. 



Broadly speaking we may say that all the substances present 

 in blood-plasma are present also in lymph, but the proteids in less 

 proportion. 



297. Lymph may also be obtained from separate regions of 

 the body, as from the lower or upper limbs, for instance, by intro- 

 ducing a fine cannula into a lymphatic vessel. In its general 

 features the lymph so obtained resembles that taken from the 

 thoracic duct of a fasting animal, but contains less solid matter, 

 from 2 to 4 p.c. The lymph which distends the subcutaneous 

 connective tissue in cases of dropsy contains still less solid matter* 

 On the other hand, lymph drawn from the lymphatics of the liver 

 even of a fasting animal is comparatively rich in solids, 6 p.c. or 

 even more ; that obtained from the lymphatics of the intestines, 

 also in a fasting animal, is intermediate in character. We may 

 repeat that the characters of lymph differ in different regions of 

 the body, and not only so but differ in each region according to 

 circumstances. Hence the characters of the lymph obtained from. 



