ITS ORIGIN. 307 



According to Nassers analyses, there is an augmentation of the 

 alcohol-extract in the lymph; this is due to the soaps that are 

 formed, and to the lactic acid and the urea. It is true that no 

 urea can be directly detected in the lymph, but we can hardly do 

 otherwise than suppose that the urea a product of the metamor- 

 phosis of tissue passes rapidly through the lymphatics before it 

 reaches the blood and is finally separated by the kidneys. The 

 fact that Schmidt* found urea in the fluid in chronic hydrocephalus, 

 might probably be taken as a proof that urea is necessarily present 

 in the lymph, if the non-existence of a simultaneous renal disease 

 had been demonstrated in this case ; and Scherer's admirable dis- 

 coveries regarding the secreted matters found in the parenchyma 

 of the spleen speak still more strongly in favour of this view. 

 Nasse certainly assumes a regressive movement of the transuda- 

 tion, or of some of its constituents, into the capillaries, and accord- 

 ing to this view these secreted matters might also be taken up 

 directly from the parenchymatous fluid by the capillaries, but not 

 by the absorbents ; but although, according to the experience of 

 several observers, the lymphatics certainly appear to make a selec- 

 tion in the substances which they absorb, yet the latest investi- 

 gations of physiologists (and especially those of Noll) regarding 

 the force which propels the lymph, indicate that it is the pressure 

 proceeding from the capillaries which chiefly occasions the move- 

 ment in the lymphatics. It not to be expected that, under the 

 pressure which the lymphatics tend to lessen, any considerable 

 part of the transudation could be reconveyed into the capillaries 

 by an opposite current. 



According to Nassers analyses, the ratio of the water to the 

 soluble salts is as 100 : 0'87l in the blood, and as 100 : 0-561 in 

 the lymph of the horse. Hence, even in the normal state, the 

 quantity of water which transudes from the capillaries is even 

 proportionally greater than that of the soluble salts which escape. 

 No one will, however, believe that the water which is formed 

 by the metamorphosis of the tissues contributes in any es- 

 sential degree to the augmentation of the water in the lymph. 

 The venous blood is consequently found to be poorer in water than 

 the arterial blood. Unfortunately the ash-analyses of the residues 

 of the lymph and serum which were instituted by Nasse, are not 

 of a nature to warrant our drawing any exact conclusions from 

 them. Future and more accurate analyses must show whether the 

 same relations hold in the lymph that Schmidt found to occur in 



* Op. cit. p. 123. 



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