CHAP. V.] THE LYMPH AND CHYLE. TRANSUDATIONS. 231 



it contains appreciable quantities of globulins. It contains a body 

 which, like glucose, reduces cupric oxide, as was first pointed out 

 by Professor Turner 1 . The cerebro-spinal liquid is occasionally much 

 increased in quantity and the analyses of the liquid made under these 

 circumstances will be considered in the next section. 



SEC. 3. THE LIQUID IN DROPSIES. 



Preliminary remarks on the mode of production of Dropsies. 



It has been stated that the lymph consists of the liquid which 

 has transuded from the capillaries and which brings into intimate 

 contact with the anatomical elements of the tissues those elements, 

 of the blood which they need for their maintenance and repair. 



Under normal circumstances, the composition of the blood, and the 

 differences between the pressure in arteries and veins are so adjusted, 

 that only as much liquid transudes from the blood-vessels as can 

 find its way back to the venous system through the lymphatics. 

 Two sets of circumstances may, however, arise to disturb the 

 normal relation. Firstly, the composition of the blood may be so 

 changed that the transudation from it into the tissues may increase 

 very greatly. This is the case when the relative proportions of the 

 water and proteids of the liquor sanguinis are disturbed, the former 

 increasing and the latter diminishing. 



Secondly, the normal difference between the arterial and venous 

 pressure may be disturbed by an actual increase of the latter, as 

 for example by some mechanical obstacle pressing upon large veins 

 and diminishing their lumen, or by an obstacle to an easy passage of 

 blood through the heart ; or, locally, the normal difference in pressure 

 may be disturbed by vaso-motor changes (as in local inflammations). 



Under any of these circumstances, dropsical accumulations may 

 result, i.e. accumulations of liquid which has transuded from the 

 capillaries into extra-vascular spaces, and which cannot be carried 

 back to the venous system by the lymphatics of liquid which must 

 be looked upon as lymph, modified though it is, no doubt, by the 

 circumstances under which it has been formed. The dropsies which 

 are due to a change in the composition of the blood are most apt 

 to be general and to affect, at any rate in the first place, the loose 

 areolar tissue, especially in dependent parts of the body. The most 

 typical example is afforded by the dropsy which occurs in the course 

 of Bright's disease, in which the loss of albumin, by transudation 

 through the renal capillaries into the urine, may in a few days so 

 alter the blood that general anasarca comes on. Another example 

 is afforded by the general dropsy which comes on in some cases of 

 anaemia, which may be due to a derangement of the metabolic pro- 

 cesses of the body, and is not necessarily (though it frequently is) de- 

 pendent upon the draining away of same important blood constituent. 



1 Turner, "Examination of the Cerebro-spinal fluid." Proceedings of the Royal 

 Society, vii., 185455, p. 89. 



