BLOOD, MORBID CONDITIONS OF THE. 



423 



mention Dr. Turner, M. Lecanu, and Dr. 

 O'Shaughnessy. Cholera blood, according to 

 these authorities, contains less water and more 

 albumen and haematosine 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. 



Chlorosis, Among other changes which oc- 

 cur in the progress of chlorosis, there is none 

 more constant than an impoverished condition 

 of the blood, which is thin, light-coloured, and 

 weakly coagulable, being deficient in fibrine, and 

 still more so in the proportion of the red par- 

 ticles. To the latter cause is to be attributed 

 the diminished temperature of the surface, to- 

 gether with the universal pallor and waxy ap- 

 pearance which those who are the subjects of 

 this disease generally exhibit. The deficiency 

 of colour in the catamenia, and the pale stain 

 which haemorrhages from the nose leave on 

 linen, are also referable to the same cause. 

 In aggravated cases, if blood be drawn from the 

 arm, the crassamentum is observed to be of a 

 pale rose colour, and small in proportion to the 

 serum. We have to regret that in this, as in 

 most other cases of morbid blood, pathologists 

 have contented themselves with a general ob- 

 servation of facts without attempting to inves- 

 tigate them with that degree of precision which 

 can alone lead to a further advancement of our 

 knowledge respecting their causes. The only 

 analyses of chlorotic blood of which I can find 

 a record are given by Mr. Jenkins in two well- 

 marked cases of chlorosis ; the one of a girl 

 aged fifteen, the other of a young woman aged 

 twenty-one. In these the blood contained 871 

 and 852 parts in a thousand, of water, respec- 

 tively, instead of 780, the healthy standard ; and 

 the colouring matter amounted to 48' 7 and 52, 

 instead of 133. The albumen and salts were in 

 the usual proportions. 



Melanosis. Although it would be foreign to 

 my present object to treat of the various morbid 

 products which may be supposed to have their 



origin in a diseased state of the blood, yet 

 there is one which seems so evidently to be the 

 result of an accidental change in that fluid, that 

 it must not be passed over without a brief 

 notice. The similarity of chemical composition 

 in the blood and in the matter of melanosis is 

 such as to leave little doubt that the material 

 of which the latter is composed has its origin 

 in the circulation, and is afterwards deposited 

 in the various parts in which it is found. The 

 different analyses of melanosis, says Andral, 

 all concur in one important point. They all 

 shew that the accidental production called 

 melanosis is formed of the different elements 

 of blood, and especially of a colouring matter 

 which more or less resembles that of the blood, 

 but which is, nevertheless, not identical with 

 it. M. Foy, in his analysis, calls this altered 

 cruor. Dr. Carswell, to whom we owe the 

 most detailed and best account of melanosis 

 which we possess, states that he has fixed its 

 seat in the blood, not only because it is seen 

 there, but because his anatomical researches 

 shew that it is there formed. He makes a 

 grand division of melanosis into true and 

 spurious; the former of which occasionally 

 makes its appearance in the circulating system, 

 a fact which is well established, while the 

 latter is more decidedly the result of chemical 

 action. Whenever healthy blood comes in 

 contact with an acid, whether in or out of the 

 body, its colour changes from red to brown or 

 black, in proportion to the strength and abund- 

 ance of the acid employed. It is to this cause 

 that we are to attribute the appearance of brown 

 or black ramifications, patches, or points, as ob- 

 served after death in the stomach and intestines. 

 To this cause also are owing the accumulations, 

 during life, of black pitchy matters in the ali- 

 mentary canal, and it is by the acidity of the 

 black vomit and its power of reddening litmus 

 paper, as we learn from Dr. Stevens, that it 

 can alone be distinguished from blood rendered 

 black by defective decarbonization or the ab- 

 sence of saline ingredients. Where a haemor- 

 rhage occurs, whether by the rupture of a large 

 vessel or by a general oozing 'from the mucous 

 membrane into the stomach or bowels, we shall 

 find the fluid ejected assume the appearance of 

 red blood or of brown or black matter, accord- 

 ing to the presence or absence of the gastric 

 juice in an acid state. Upon this almost acci- 

 dental circumstance, then, will it depend whether 

 we are to designate the disease haematemesis or 

 melaena, there being in reality no essential dif- 

 ference between the two diseases. The black 

 discolouration of blood which occurs whenever 

 it becomes stagnant from retarded or interrupted 

 circulation, will, by those who follow the views 

 of Dr. Stevens, be attributed to a similar cause. 

 According to that author it is the presence of 

 carbonic acid which acts like other acids in ren- 

 dering venous blood dark, and it is its abstrac- 

 tion by oxygen which, combined with the action 

 of the saline matters it contains, restores it to 

 its scarlet hue. 



The foregoing are among the more pro- 

 minent diseases in which the blood has been 

 observed to undergo changes either directly 



