It may not be out of place here to observe, that in this disease not only does the blood it self contain urea, but all those ,effusions also which are formed from it, and which take place in the different serous cavities. I have repeat edly detected urea in these cases in the serous effusion into the ventricles of the brain ; and Dr. Barlow found it in one case, 1st, in abun dance in the ventricles of the brain ; 2dly, scantily in the effusion into the pleura and peri cardium ; and 3dly, in :abundance in the peri toneum. In a second case of a similar nature urea was obtained in abundance from the fluid of the pericardium. In a third the effusion collected after death from the pleura of a man who had suffered from general dropsy and mot tied kidney, yielded a very satisfactory specimen of urea.
I have dwelt at some length on this subject, as it is only of late years that the attention of the medical world has been drawn to it through the writings of Dr. Bright, and still more re cently that the morbid changes presented in the blood have been investigated.
this complaint the blood un questionably undergoes some material change, although its nature has not hitherto been very successfully investigated. This may be inferred from the great length of time during which it is capable of resisting putrefaction, a circumstance first noticed by Rollo, and which, though doubted by some authors, I have oppor tunities of confirming in several instances. Nicolas and Gieudeville have observed that it contains an increase of serum and very little fibrine, but this is not borne out by my own • experience as deduced from many specimens of diabetic blood which I have examined ; neither can its antiseptic qualities be attributed to any deficiency in the proportion of azote, for Dr. Prout, who has made accurate experitnents to determine this point, has found it not to differ in this respect from the standard of health. The most eminent chemists both abroad and in this country have endeavoured in vain to de tect sugar in diabetic blood. Dr. Wollaston ascertained that the smallest portion of saccha rine matter added to serum previously to its coagulation by heat, prevents the subsequent crystallization of the salts it contains, yet that in diabetic serum those salts crystallized with the same facility as in that procured from a person in health. The same reasoning as that which has been adduced to prove that urea may be formed in the blood, although it is not to be detected there while the kidneys perform their office, will also apply to the existence of sugar in the blood of those affected with this disease.
I am not aware that the arterial blood has been made the subject of experiment, and yet it is possible that it might exist in the arteries alone, for we have only to suppose it to enter the cir culation with the chyle, and after having been carried through the lungs, the left cavities of the heart, and the aorta, to be again withdrawn from the circulation by the kidneys. I do not pre tend, however, that this supposition carries with it any degree of probability.
is no disease in which the blood undergoes more remarkable changes than in malignant cholera; not indeed in the in cipient stage, as affirmed by Dr. Stevens, but in direct proportion to the intensity and duration of the collapse. In appearance it is thick and dark, bearing a strong resemblance to treacle or tar. It is of high specific gravity, the serum varying from to 1.045 at 60 Fahr.; and according to M. Lecanu, the solid matter which it contains is sometimes double that of the healthy proportion. Most of its physical cha racters are satisfactorily accounted for by its analysis, which has been accurately made by several eminent chemists, among whom we may mention Dr. Turner, M. Lecanu, and Dr. O'Shaughnessy. Cholera blood, according to these authorities, contains less water and more albumen and Immatosine than healthy blood, and its salts are in unusually small quantity, or almost entirely wanting. Dr. O'Shaughnessy, who has detected urea in cholera blood, states that the summary of his experiments denotes a great but variable deficiency of water in the blood of four malignant cholera cases; a total absence of carbonate of soda in two ; its occur rence in an almost infinitessimally small propor tion in one ; and a remarkable diminution of the other saline ingredients : lastly, the micro scopic structure of the blood and its capability of aeration are shewn to be preserved. The cause of the dark colour of the blood in cholera is a point which we are told by Dr. Turner is by no means decided. Dr. Thomson and Dr. O'Shaughnessy are at variance on the question of its susceptibility of arterialization. Dr. Stevens rather unphilosophically makes its dark colour to depend primarily on the poi sonous cause of contagion, yet attributes it also to a deficiency in the proportion of saline matter. It is probably not owing to either of these causes, but to a defective circulation through the lungs, from which the blue livid tint frequently observed over the surface of the limbs likewise originates. The corresponding diminution of animal heat gives countenance to this supposition.