528 



BLOOD. 



something like use in the -globules, that one feels 

 strongly tempted to leap the boundary, and declare 

 and speculate about real use ; but alas ! there is " a 

 gulf fixed," and that gulf is fathomless. 



Even in the humble matter of a chemical analysis, 

 these globules set our most careful operations at 

 defiance. We can never be sure that we have 

 separated them entirely from the other parts of the 

 blood, and in those cases wherein this appears to 

 have been most closely approximated, the greater 

 part of the products obtained from their decomposition 

 were found to be the same as those in the rest of the 

 blood only, about an eightieth part of their volume 

 resisted the fire, and of that more than the half, and 

 about one hundred and fiftieth part of the active 

 mass, consisted of oxide of iron. When merely acted 

 upon by saline mixtures, but not decomposed, these 

 particles show much sensibility to chemical action. 

 Some substances make them contract, some expand 

 them, some brighten their colour, and some render 

 them darker ; but in every case these are the ultimate 

 results, and we are unable to draw from them any 

 other conclusion than that these bodies are very 

 sensible to chemical action ; but what are their 

 relative degrees of sensibility when in the living 

 circulation, and when out of it, we have no means of 

 ascertaining. 



It is usually understood, that too free a use of 

 common culinary salt darkens not only the colour of 

 the blood, but the complexion generally. Salt pro- 

 visions have a tendency to produce scurvy, in which 

 the blood is dark ; and a darkening effect, with a 

 tendency to the irritation of the smaller vessels, is 

 produced by too free a use of stimulating liquors. 

 .But, any conclusion which we might fancy ourselves 

 able to draw from these cases is met by others of a 

 quite opposite kind, or at least, apparently arising 

 from opposite causes. Exposure to cold, or any tiling 

 which gives great rigidity to the small vessels near 

 the surface, produces an effect analogous to that of 

 stimulating liquors ; and too meagre food brings on 

 scurvy as well as salt provisions. Besides, as we 

 never can obtain any other than a systematic result 

 when we make experiments on the living body, we 

 are not able clearly to decide which is the part first 

 and chiefly affected. 



The most important part of the inquiry is certainly 

 that which relates to the change of the blood in respi- 

 ration, and the consequent differences between venous 

 and arterial blood ; and it is in the red particles that 

 this change, or the difference which this change pro- 

 duces, is most apparent. Whence the excess of carbon 

 with which the blood becomes loaded in its return 

 from the systematic circulation, and which imparts to 

 it its dark colour, comes, we are unable to ascertain. 

 It may com.e in part from those portions of the body 

 which the blood reaches, it may come from the sub- 

 stances which are taken up by the absorbents, or it 

 may come from the alimentary chyle. It is indeed 

 not improbable that it comes from all three ; for the 

 blood in the vein has assumed the dark colour at an 

 early stage of its return ; and the matters which the 

 thoracic duct empties into the subclavian, whether 

 products of digestion or of absorption, are not tit for 

 the circulation until they ha*e undergone the opera- 

 tion of the air in the breathing apparatus. 



It is doubtful whether the red globules of the blood 

 owe the whole of their colour to the presence of the 

 iron ; but the iron does at all events accompany the 



colouring matter rather than the other parts. It is 

 in such quantity that there are computed to be about 

 two ounces in the blood of an ordinary man in ;i 

 healthy state. There is also a trace of iron, although 

 a fainter trace, in red muscle; and the redder the 

 muscle, the trace of iron is the more apparent. It 

 does not appear to exist, at least in such quantity as to 

 be detectible by any of the common chemical means, 

 in those parts of the body which are not reddish, or 

 in those animals which have not red blood; but these 

 facts are not conclusive evidences against its existing 

 there in a very minute quantity. 



The red particles of the blood and the muscles arc 

 the parts of the animal most easily excited ; and we 

 have already seen that the crassamentum, or cruor, of 

 the blood, including both the pant which can be con- 

 verted into fibrin and the red particles which accom- 

 pany that in the blood, and the fibrin which is deve- 

 loped in the muscles and appears to derive its colour 

 frorr that of the blood, are excited in the same way 

 by very different causes. From these coincidences, 

 it is very difficult to refrain from speculating about 

 the rationale of muscular action. We do not mean as 

 to whether it is mechanical or chemical ; because, 

 although as being displayed in and by matter which 

 still retains its properties as matter, though subdued 

 or suspended while that matter forms part of the liv- 

 ing animal, it must be both mechanical and chemical 

 in its relations, yet in itself and primary it is neither; 

 it is physiological not physical using the first of 

 these terms as descriptive of the phenomena of organ- 

 isation, and the second as descriptive of the pheno- 

 mena of matter when not organised. 



Still, this, which we may properly regard as the 

 primary action of animals, that to w hich all their other 

 actions are owing, and in the suspension of which all 

 these are suspended, must be regarded as material 

 that is as a result of matter and not of mind. Mind 

 has no mechanical action. Knowledge is its province, 

 but it cannot of itself stir one atom of matter a single 

 hairbreadth. Hence in man the organisation and the 

 life of the animal are as necessary and perfect for 

 mechanical purposes as the thought is for mental 

 ones ; and thus far man is as subject to death and 

 material dissolution as any other creature, and in all 

 the states and functions of his material frame he 

 follows the same law as the rest. It were in vain, 

 therefore, to seek for an explanation of animal action 

 as a result of any thing like mind ; because mind 

 could not accomplish it without having the properties 

 of matter, that is, without being matter. When, 

 therefore, we speak of " animal spirits" as being the 

 cause of activity, we only encumber ourselves with 

 additional words without any additional meaning ; 

 and in the individual case, the words should be re- 

 versed, and that which we call animal spirits should 

 be called a " spirited animal," the word spirit in that 

 case having reference to the energy or manner of the 

 action, not to its cause. 



But if this primary action of the animal be, as it 

 unquestionably is, a phenomenon or property of mat- 

 ter only, with what other portion of the material cre- 

 ation shall we connect it, or where else shall we find 

 its counterpart? Where too shall we look for its 

 origin? for unless we go back to the moment of crea- 

 tion, we must have a natural cause for every natural 

 effect a natural antecedent for every natural conse- 

 quent ; otherwise, we stand in need of creation and 

 miracle every day ; by which means the original ere- 



