2 S6 PROD UCTION AND ABSORPTION OF I J MPH. 
forming a colourless clot of fibrin. It contains from 2 to 8 parts 
per 100 of solids, of which about 1 per cent, consists of inorganic 
salts, while the rest is made up chiefly of proteids. The proteids are 
similar to those of the blond plasma : and it seems that the process of 
clotting is identical in the two fluids. The salts vary very little in 
different samples of lymph, and are generally described as being present 
in exactly the same proportions as in the blood plasma from which the 
analysed specimen of lymph was derived. Hamburger has recently 
called attention to the existence of minute differences of composition in 
the salts of the two fluids, and this difference may be credibly ascribed 
to chemical changes effected in the lymph by the tissues over which it 
has flowed. All specimens of lymph contain leucocytes, chiefly of the 
small uninuclear variety; these are found in greater numbers after the 
lymph lias pissed through a lymphatic gland. Further information re- 
garding the composition of lymph will bo found in the article on lymph 
and serous exudations (p. 181). 
The similarity in composition between liquor sanguinis and lymph 
suggests that the latter may be regarded as part of the plasma which 
exudes through the capillary wall, bathes all the tissue elements, and is 
collected by the lymphatics into the thoracic duct to be returned again 
to the blood. 
Forces involved in lymph production.— Older theories.— As to 
the forces involved in its production and the use of this fluid in the 
functions of the body, the most various views have been held. Asellius, 1 
who discovered the lacteals in 1622, thought that these ducts 
carried the foodstuffs from the intestines to the liver to be there 
elaborated into blood. In order to explain the filling of the lacteals 
from the intestines, Asellius invoked the aid of the complicated 
mechanism which had already been imagined by Avicenna to account 
for the filling of the mesenteric veins. He explained the passage of 
chyle to the liver as due partly to the intestinal movements and partly 
to the suction-action of the blood vessels and of the liver itself. The 
chief factor however was, according to him, the suction-action exerted 
by the open mouths of the lacteals themselves, and he compares the 
latter to leeches, which suck blood from any surface to which they are 
applied. This theory was overthrown by Pecquet 2 by the discovery of 
the connection of the lacteals with the thoracic duct and through this 
with the venous system. The general lymphatics were discovered 
by Budbeck 3 and Bartholin 4 almost simultaneously. In these authors 
we meet with the first conception of lymph apart from absorbed 
foodstuffs ; moreover, Bartholin, assuming that this lymph is formed 
from the blood, discusses the possible ways by which the fluid could 
get from blood vessels to lymphatics. He thinks it possible that 
there may be a direct communication between lymphatics and blood 
vessels, but is more inclined to the view that the communication is 
indirect by means of the parenchyma of the organs. Failing to remark 
what Eudbeck had already noticed, namely, that the lymph had a salt 
taste, and like blood clotted spontaneously, he describes the lymph as 
pure water, and imagines that from the blood vessels there is a 
1 " De lactibus sive lacteis venis," Basel, 1628. 
2 " Experiments, nova anatoniica, " Paris, 1654. 
3 "Nova exercitatio anatomica, etc." 1653. 
4 " Vasa lymphatica nuper in animantibus inventa," Hafnia?, 1653. 
