BLOOD. 



There are some rather curious analogies which 

 would lead us .to suppose that there is some very 

 extensive connexion, or at all events resemblance, 

 between the fibrin of the blood, and the muscles, and 

 aUo between the serum of the blood and the mem- 

 branous tissues of the body. In many animals the 

 muscles approach to the colour of blood, and they 

 are the only parts of the animal which do so. Little 

 useful inference can indeed be drawn from this, 

 because the muscles of many of the red-blooded 

 animals are white, or nearly so ; and all muscles may 

 be made white by repealed washing, while the fibrin 

 of which chiefly they are composed continues un- 

 changed. The same has been remarked of the cras- 

 samentum of blood ; and when the two have been 

 thus freed from colouring matter, they appear as if 

 portions of the same substance. 



There are also some curious coincidences between 

 the coagulation of the crassamentum of the blood, and 

 the contraction of the muscles. They are both ope- 

 rations which we do not understand ; and though we 

 call the one an attraction which those particles of the 

 blood which are fit for forming fibrin have for each 

 other, and not for the particles of the scrum, or for 

 the coats of the vessel in which the blood is contained, 

 and the other irritability, or any thing else, or though 

 we call each a different kind of attraction, or both the 

 same kind, only modified by the dift'erent textures of 

 the substances in which they act, we make no pro- 

 gress whatever toward the understanding of them. 

 We have more words certainly ; and those words 

 may, as words often do in other cases, satisfy the 

 ignorant, and lead them to conclude that we have 

 more knowledge than they, but they would not make 

 us one jot the wiser. 



But though this very peculiar and incomprehensible 

 action takes place in different substances apparently, 

 and also in dift'erent states of those substances, as 

 contraction in the living muscle, and coagulation in 

 the blood after it is removed from the body, or when 

 it has become stagnant, yet it is possible that they 

 are one and the same action, differently modified. 

 That unnaturally violent contraction of the muscles 

 to which the name of cramp is given, bears nearly the 

 same relation to the healthy action of the muscle, 

 that coagulation bears to the healthy state of the blood. 

 It appears, from the phenomena which occur in re- 

 cent blood, and from its consistency when it is taken 

 from the vessel of the living body, that there is no 

 fibrin ready formed in it, into any thing that we can 

 call an organic structure even of the most rudimental 

 kind. There is only, so to speak, a capacity in the 

 particles to form this substance, under circumstances 

 which are favourable to it. If the fluid passes quietly 

 into a state of repose, there is coagulation, but not the 

 formation of fibrin, nor can any future operation turn 

 the jelly-like substance thus formed (which however 

 is not jelly,) into fibrous matter. So also if it is 

 violently agitated, the tendency to form fibrin is de- 

 stroyed, and no subsequent treatment can then favour 

 the spontaneous coagulation. It is said, that if the 

 agitation is violent enough, the uncoagulable result 

 acquires generally a considerable degree of that 

 milky odour (but not the colour of course) which the 

 serum of blood gives out when heated. It is also 

 said to have some resemblance to the catameniary 

 fluid, which, though of the colour of the vital fluid, is 

 understood to be really a secretion of the mammae, 

 incoagulable, and not forming fibrin by any treatment 



It is to be regretted that the experiments of the late 

 Dr. John Smith, of Edinburgh, upon the nature of 

 this secretion, should have been lost to the world by 

 his premature death ; for it is a subject which, 

 worked out with due care, and without hypothesis, 

 is calculated to throw light upon some of the most 

 curious points in physiology, more especially the un- 

 known bourne which separates, and at the same time 

 connects, the blood of every two consecutive genera- 

 tions. This is a subject, however, upon which, for 

 obvious reasons, we cannot enter in a popular work. 



In like manner as that portion of the blood which 

 is predisposed to the formation of fibrin passes into 

 coagulum, when the blood as it comes from the 

 living vessel is allowed to rest, so the muscle, when 

 it passes from the living to the dead state, under 

 ordinary circumstances, passes into a state of rigidity ; 

 or all the muscles pass equally into a state of con- 

 traction, from which they do not again relax till 

 their substance begins to yield to the ordinary action 

 of decomposition. Here also there is a resemblance 

 between the coagulable portion of the blood, in so far 

 as we can suppose a resemblance to be traceable 

 between a fluid apparently homogeneous, and a soft 

 solid made up of fibrous fasciculi. 



One of the most remarkable evidences of this 

 similarity in the blood and the muscle, is to be found 

 in the similar effects of certain violent kinds of action 

 upon both. Almost all those actions differ in the 

 agents by which they are produced, and indeed in 

 most of the circumstances, but they agree in pre- 

 venting the coagulation of the blood and the stiffening 

 of the muscles, and they also all, in so far as we can 

 understand the rationale of their action, agree in 

 bearing some resemblance to that rapid or violent 

 agitation of the blood which destroys its tendency to 

 coagulate when out of the body. It is rather remark- 

 able, and should show us that, in our physiological 

 investigations, we ought not to lay too much stress 

 upon mechanical or chemical appearances or effects, 

 that some of those actions are merely momentary, 

 and some of more prolonged duration, some of them 

 act by direct mechanical agency, some have nothing 

 of common mechanics in them, some are produced 

 by vegetable agents, and some by animal ones, and 

 some have their proximate, if not their primary causes 

 in the body itself. 



Gun-shot wounds may be mentioned as one in- 

 stance, and the more speedily that death ensues after 

 the receiving of the wound, the state of the body is 

 the more completely relaxed. The wind of a can- 

 non shot when it causes death, which it sometimes 

 does when it passes very near, has almost the same 

 effect in relaxing the body as a gun-shot wound ; 

 and instant death from a* blow on the stomach, or 

 from a concussion or other injury to the brain has 

 still the same effect. These last two instances are 

 against the hypothesis that either the blood or the 

 muscles can be the peculiar seat of life ; for the 

 injury done to the source of chylefaction or to that of 

 the nervous energy produces the same effect on the 

 blood and the muscles, as other injuries which are 

 understood to go more directly to those parts of the 

 body. Perhaps the most complete prostration of the 

 body, in which the muscles remain quite soft and 

 the blood liquid, is that produced by electric matter 

 when its violence is sufficient to produce death, 

 whether it come in the form of lightning or of any 

 other ; but if there is no topical violence produced 



