126 Disturbances of Circulation. 



This blood precipitate is found microscopically not only at the 

 site of haemorrhage, especially in the amoeboid cells which are 

 loaded with it, but also in the nearest lymph glands which are often 

 found tinted all through by a rusty, reddish-brown color from the 

 quantity of blood pigment conveyed to them. In the dead body, on 

 account of sulphur products (sulphuretted hydrogen) of the 

 cadaveric bacteria, the site of a haemorrhagic infiltration may be 

 found changed to a slate gray to black hue by the sulphur com- 

 binations ; in life, too, in places where similar bacterial accumula- 

 tions and fermentations occur (intestine, abscess cavities, fistulous 

 paths, mycotic diseases of the bladder) the pigment may undergo 

 the same changes in color and thereafter remain as evidence of 

 previous haemorrhage. 



Dropsy. Hydrops and Oedema. 



Excessive accumulation of the tissue fluid or lymph in the 

 lymph spaces, lymph vessels and serous sacs (Ivmph sacs) is 

 spoken of as dropsy, hydrops (from vSa>p, water) or hydropsia, 

 and. if the accumulation has occasioned swelling of the tissue, as 

 oedema (from or5a;'. to swell). The process itself is described as 

 a dropsical transudation (from sudarc, to sweat) ; the accumulated 

 fluid as a transudate. Neither the process nor the transuded fluid 

 is essentially anything more than a quantitative disturbance of 

 physiological lymph-production. Lymph is originally derived from 

 the blood, and is regarded by many as a secretory product of the 

 endothelium of the capillaries, although the blood pressure is also 

 maintained as a factor in its production and accumulation, affecting 

 the filtration of the liquid part of the blood through the capillary 

 walls. [Whether the physical processes of dialysis and osmosis 

 should also be invoked here is debated. Lazarus-Barlow, in dis- 

 cussing the vital transudation of lymph, urges the importance of 

 tissue demands for lymph both for purposes of nutrition and for 

 its influence in diluting and removing various products of their 

 metabolic activities or of their degeneration, and points out that 

 in this last case there exists a possible explanation for the per- 

 sistence of an oedematous process in case the excretory organs as 

 the kidneys fail of eliminating from the blood the various waste 

 materials. Thus if, in a case of nephritis, the blood becomes sur- 

 charged with waste materials and if at the same time such waste 

 in a local area of special activity or of degeneration is excessive, 



