BLOOD, MORBID CONDITIONS OF THE. 



4-29 



cognizable by our senses, or discoverable by 

 those chemical and mechanical means which 

 we are enabled to call to our assistance. There 

 are, however, other morbid conditions the ex- 

 istence of which is equally certain, although 

 their essence is of such a doubtful nature that 

 it defies detection by the coarse instruments 

 and the limited skill which man, in the present 

 state of his knowledge, is enabled to employ. 

 In the exanthematous diseases the blood par- 

 takes of the general disorder of the system. Dr. 

 Home of Edinburgh* succeeded in reproducing 

 measles by inoculation with blood drawn from 

 a superficial vein in one of the patches of 

 eruption which cover the skin in that disorder ; 

 and though others have failed in this experi- 

 ment, it has been successfully and often re- 

 peated by Professor Speranza of Mantua. 

 Pregnant females affected with small-pox, or 

 even exposed to its virus, though they may 

 have had the disease, have often imparted it to 

 the foetus in utero,f and syphilis has been 

 communicated in the same manner. Professor 

 Coleman has proved by experiment that the 

 blood of a glandered horse will impart glan- 

 ders if infused into the veins of a healthy 

 animal. Dupuy and Leuret have thus pro- 

 duced malignant pustule ; transfusion of the 

 blood of a mangy dog has produced mange in 

 another; and, according to Dr. Heitwich of 

 Berlin, the blood of a rabid animal will by inocu- 

 lation communicate the disease. A remarkable 

 instance is related by Duhamel, in which a 

 butcher became affected with a malignant pus- 

 tular disease in consequence of having put into 

 his mouth the knife with which he had slaugh- 

 tered an over-driven ox. Another individual 

 lost his life from sphacelus of the arm in con- 

 sequence of a wound in the palm of his hand, 

 accidentally inflicted by a bone of the same 

 animal; and in two women who received some 

 drops of its blood, the one on her hand, the 

 other on her check, inflammations ensued which 

 rapidly terminated in gangrene. 



Although in all these instances there can be 

 no doubt that the blood was in a poisonous 

 state, there is no reason to suppose that this 

 could have been foretold by any thing remark- 

 able in its appearance or sensible qualities. 

 Scarcely more successful in general has been 

 the search for extraneous poisons, which never- 

 theless have appeared from collateral circum- 

 stances to have entered the circulation, or have 

 even been purposely introduced into it. Dr.Chris- 

 tisonj has cited a sufficient number of cases 

 where poisons swallowed have been afterwards 

 found in the blood, to shew that we must not 

 infer their absence from our inability in most 

 cases to abstract them in a separate form ; and 

 he further demonstrates how erroneous such an 

 inference might be by stating that Dr. Coindet 

 and himself, after destroying a dog in thirty 

 seconds by injecting 8| grains of oxalic acid 

 into the femoral vein, endeavoured in vain to 



* Duncan's Medical Commentaries, vol. xix. 

 p. 213. 



t Edinb. Med. and Surg. Journ. for April 1807. 

 Med.-Chir. Trans, vol. i. p. 272. 



J Christison on Poisons, p. 14. 



detect any portion of it in the blood of the iliac 

 vein and vena cava collected immediately after 

 death, although it is highly improbable that it 

 could have passed off by any of the secretions 

 in so short a time. 



The chief obstacles by which we are opposed 

 in such researches are minuteness of quantity 

 and decomposition. When only a few grains 

 of a poison are absorbed, and thence diffused 

 not only through the whole mass of circulating 

 blood, but likewise among all the various 

 tissues and solids of the body, being moreover 

 carried off by the kidneys, perhaps nearly as 

 fast as they enter by the circulation, it cannot 

 be matter of surprise, however delicate our 

 tests may be, that they are seldom to be met 

 with even where still retaining their chemical 

 characters. When we consider, however, that 

 reagents which produce a change of properties 

 in those bodies with which they are brought in 

 contact do probably themselves undergo a cor- 

 responding change, we shall readily perceive 

 that our difficulties will be still further in- 

 creased on this account. 



The products of diseased action, and espe- 

 cially pus, have been often met with, as well in 

 the arteries and veins, as in the cavities of the 

 heart ; but it yet remains a matter of doubt 

 whether these are actually formed in the blood, 

 or whether, as seems to me more probable, 

 they are not rather carried into the circulation 

 from other parts in a degenerate or diseased 

 state, or are the products of inflammation in 

 the lining membrane of the bloodvessels them- 

 selves. 



With respect to those cases where worms 

 and insects are said to have appeared in the 

 blood, whereof many are recorded, some are 

 referrible to the head of false polypi, the shape 

 of which has misled the observer, others to 

 deception or the accidental presence of insects 

 or their ova in the receiving vessel ; and though 

 we cannot deny the possibility that parasitical 

 animals may exist in the fluids as well as in the 

 closed cavities and solids of the body, yet we 

 require better evidence than has yet been ad- 

 duced to confirm our belief in the existence of 

 entozoa in the circulating current. In a recent 

 case brought forward by Mr. Bushnan,* and 

 learnedly illustrated by that gentleman, it 

 would, I confess, have carried more conviction 

 to my mind, had he himself watched the blood 

 from the moment of its quitting the vein until 

 the larvae which he describes were seen swim- 

 ming in its serum. In such extraordinary cases 

 the mind is not satisfied with anything short 

 of moral certainty. 



From what has been set forth in the fore- 

 going pages, it will be perceived that our 

 knowledge on the subject discussed in them 

 yet remains extremely defective. We learn, 

 indeed, that under the existence of disease 

 the different constituents of the blood are 

 liable to morbid increase or diminution as well 

 as to certain alterations in their sensible qua- 

 lities, hitherto less accurately examined ; that 



* History of a case in which animals were found 

 in blood, &c. 



