ORIGIN AND USES OF THE LYMPH 261 



cytes). These exist, not only in the clear lymph, 'but in the opaque 

 liquid contained in the lacteals during absorption. Eighty-two hundred 

 leucocytes have been counted in 0.06 1 cubic inch (i cubic centimeter) 

 of lymph from a dog. 



The leucocytes found in lymph and chyle are rather less uniform in 

 size and general appearance than the leucocytes of the blood. Their 

 average diameter is about ^Vo of an inch ( IO /*); but some are larger, 

 and others are as small as ^-fa of an inch (5 /*). Some of these cor- 

 puscles are quite clear and transparent, presenting but few granules 

 and an indistinct nuclear appearance in their centre ; but others are 

 granular and quite opaque. They present the same adhesive character 

 in the lymph as in the blood, and frequently they are found collected 

 in masses in different parts of the lymphatic system. In other regards, 

 these bodies present the same characters as the leucocytes of the blood, 

 and they need not, therefore, be further described, but the variety 

 known as lymphocytes predominates. In addition to leucocytes 

 and a certain number of fatty granules, a few small clear globules or 

 granules, about y^Vo of an ^ ncn (3-3 /*) i n diameter are almost con- 

 stantly present in the lymph. They are insoluble in ether and acetic 

 acid but are dissolved by ammonia. 



Origin and Uses of the Lymph. There can hardly be any doubt 

 concerning the source of most of the liquid portions of the lymph, for 

 they can be derived only from the blood. Although the exact relations 

 between the smallest lymphatics and the bloodvessels have not been 

 made out in all parts of the system, there is manifestly no anatomical 

 reason why water, mixed with albuminous matters and holding salts in 

 solution, should not pass from the blood into the lymphatics ; and this 

 is rendered nearly certain by the fact that the lymphatics surround many 

 of the bloodvessels. In comparing the composition of the lymph with 

 that of blood-plasma, it is seen that their constituents are nearly identi- 

 cal, the only variations being in their relative proportions. 



One of the most important physiological facts in the chemical history 

 of the lymph is the constant existence of a considerable proportion of 

 urea. This can not be derived from the blood, for its proportion is 

 greater in the lymph, notwithstanding the fact that this liquid is being 

 constantly discharged into the bloodvessels. The urea existing in the 

 lymph probably is derived in some way from the liver ; it is discharged 

 then into the blood, and is constantly being eliminated by the kidneys. 



The positive facts on which to base any precise ideas in regard to 

 the general office of the lymph are not many. From the composition 

 of this liquid, its mode of circulation and the fact that it is being con- 

 stantly discharged into the blood, it would not seem of itself to have 



