VOL. XIX.] PHILOSOPHICAL TRANSACTIONS. 107 



former with much greater force than the latter; though in the left ventricle of 

 the heart and arteries too I have sometimes met with polypuses very large : but 

 I always found the right auricle and ventricle to be furnished with the largest. 



Blackish urine I believe is commonly observed in many feverish indispositions, 

 where the blood is either partially obstructed in its return by the veins of the- 

 kidneys, or through its great velocity in passing the kidneys, when some parts of 

 the globules of the blood also pass out at the urinary pores in the sides of the 

 blood-vessels, and those globules being broken exhibit those blackish bodies 

 which appear in the sediment of the urine. In these cases, the serum of the 

 blood passes off with the urine ; for by evaporating such urine by heat, as in a 

 spoon over the candle, it will become thick, like the true serum of the blood. 



Obstructions commonly begin in the most capillary vessels first, as I have fre- 

 quently observed in viewing the transparent fins of divers living fishes with a 

 microscope ; and though it has been hitherto commonly supposed, that veins 

 and arteries are all equally lessened at their extremities, yet I am of opinion, 

 that the extremities of divers blood-vessels are much larger than their fellows ; 

 hence an account may be given of the partial circulation of the blood, and yet 

 mortifications not necessarily succeed, as in the present case. For the kidney 

 here being vastly distended, which proceeded from a retardation of the refluent 

 blood and lympha, it is conceivable that the obstructions began in the mem- 

 branes, which compose the parietes of the trunks of the veins and lymphasducts, 

 whence an intumescence necessarily follows, and the cavities of those vessels are 

 lessened ; consequently the refluent blood or lympha not being duly discharged, 

 those larger vessels are necessarily distended between their tumefied sides with 

 compressed cavities, and their extremities at the arteries. Thus we may appre- 

 hend how a part remains tumefied under a partial circulation, and may (when 

 no bad juices taint the blood and lympha) continue so for some months, nay 

 years, as in the present case, without any disorder to the patient ; but on such 

 motions of the body, as accelerate the motions of the blood, at the extremities 

 of the vessels when there is a greater quantity of blood iinported than can be 

 discharged by the veins ; whence a sudden intumescence arises, and pains neces- 

 sarily follow. What astringent medicines avail in such like cases is difficult to 

 conceive ; but aperitives rnight be serviceable. Loss of appetite, bad digestion, 

 &c. attend nephritic cases, by the nervous coinmunications of those of the 

 kidney with the stoinach, &c. whence the tone of that part, as well as the in- 

 testines, especially the colon, becomes vitiated, and subject to frequent disorders, 

 especially vomiting and colic pains. By the tone of tliat part, I mean that 

 proper distribution of the nervous ramifications within the part when distended, 

 as in this case, and intestinal ruptures, as they are called, and the like ; or 



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