AND ITS RELATIONS TO THE LIVING ORGANISM. 273 



the "cup," which may be generally considered to indicate a high degree of 

 Inflammation. The physical changes to which the blood is subjected when 

 drawn from the vessels are, that it is brought to rest, that its temperature is 

 reduced, and that it is exposed to the action of the air. It may easily be 

 shown, however, that its coagulation cannot be attributed to either of these 

 conditions. For in the first place if the blood be continually agitated in a 

 bottle, though its coagulation is delayed, it will at last take place in shreds 

 or insulated portions; that rest is not the cause of its coagulation (as some 

 have supposed) is proved by the fact that, if a portion of blood be included 

 between two ligatures in a living vessel, it will remain fluid for a consider- 

 able time; 1 as it also will when effused into the midst of living tissue.*, or 

 kept in a state of stagnation in parts affected Avith inflammation. Thus 

 Mr. Gulliver, besides other instances, mentions a remarkable case witnessed 

 by himself, in which a collection of blood which had been effused in con- 

 sequence of a bruise on the loins, was found uncoagulated when let out 

 twenty-eight days afterwards ; it measured five ounces, was as liquid as 

 blood just drawn from a vein, and showed the normal characters when ex- 

 amined microscopically; and it coagulated in a cup in less than thirty 

 minutes. 2 And Mr. Paget mentions that he has known the blood remain 

 fluid in the vessels of an inflamed part, though in a state of complete stag- 

 nation, for as long as three days. 3 Again, so far from coagulation being 

 promoted by cold, it can be shown to be accelerated by moderate warmth, 

 the natural heat of the body from which the blood is taken appearing to be 

 most favorable to it; but the coagulating power appears to be destroyed by 

 a temperature of about 150, blood heated to that point remaining perma- 

 nently fluid. 4 On the other hand, the coagulation is retarded by cold ; but 

 the coagulating power is not destroyed even by extreme cold ; for if blood 

 be frozen immediately that it is drawn, it will coagulate on being thawed. 

 Lastly, although coagulation is accelerated by exposure to air, it is not pre- 

 vented by complete exclusion from it, as is proved by its taking place in a 

 vacuum, or in a shut sac within the dead body : complete exclusion from 

 the air, however, does retard the change ; as may be easily shown by caus- 

 ing blood to flow into a vessel containing oil, which will form an impervious 

 coating on its surface, and will occasion the coagulation to take place so 

 slowly, that the red particles have time to subside, and the upper stratum 

 of the clot to be colorless. 5 The effect of the addition of strong solutions 

 of neutral salts to fresh blood, is usually to retard, and sometimes even to 

 prevent, its coagulation ; and the same effect is produced by many vegetable 

 substances, particularly those of the narcotic and sedative class, such as 

 opium,, belladonna, aconite, hyoscyamus, digitalis, and tea or coffee in strong 

 infusion. 6 The action of most of those substances, however, which preserve 



1 The testimony of all experimenters is in accordance on this point, although they 

 differ as to the length of time that elapses before coagulation commences. Mr. Gul- 

 liver states that out of rmny trials made by him, the coagulation commenced within 

 two hours in only a few instances ; more commonly, three, four, or five hours elapsed 

 before any clot was formed ; and in one instance, the coagulation was incomplete at 

 the end of twenty-four hours. In all these experiments, the blood coagulated in the 

 course of a few minutes, when withdrawn from the living vessels. See Mr. Gul- 

 liver's edition of Hewson's Works, p. 23. 



2 Op. cit., p. 17. 3 Lectures on Surgical Pathology, vol. i, p. 310. 



4 Gulliver, op. cit., pp. 4, 5. 



5 Dr. Babington in Medico-Chirurgical Transactions, vol. xvi. 



6 See Dr. J. Davy's Anatomical and Physiological Researches, vol. ii, pp. 101, 

 102; and Mr. Prater's Experimental Inquiries in Chemical Physiology, pp. 59, 63, 

 etc. A copious table of the results of their experiments is given in Mr. Ancell's 

 Lectures on the Physiology and Pathology of the Blood, in the Lancet for Dec. 

 21st, 1839. 



