August 23, iSSS] 



NATURE 



403 



oxyhemoglobin. The tissues, then, do not use up all the oxygen 

 of the oxyhemoglobin, and they cannot, therefore, have a stronger 

 affinity for the oxygen than haemoglobin has. On the other hand, 

 as the tissues undoubtedly seize hold of the oxygen, and rob the 

 hemoglobin of it, it would appear as if they really had a stronger 

 affinity for the oxygen. There is thus a contradiction according 

 to Fleischl von Marxow, and it shows that our theories as to the 

 ultimate chemical changes of respiration are not valid. 



It might be objected at this point that the death of an animal 

 from asphyxia, while oxygen still remains in its blood, is no proof 

 that the tissues have lost their power of removing oxygen from 

 oxyhemoglobin. It only indicates that certain tissues, probably 

 those of the nervous centres, require more oxygen than is supplied 

 to them ; and, therefore, this part of the bodily mechanism is 

 arrested, with the result of somatic death. Other tissues still live, 

 and use up oxygen so long as their vitality lasts. At the same 

 time, I am willing to admit that it is a striking circumstance that 

 the nervous tissues stop working before they have exhausted every 

 atom of oxygen in the blood. 



But if tissues have, as all admit, an affinity for oxygen, and if, 

 at the same time we grant, for the sake of argument, that this 

 affinity is not strong enough to dissociate the oxygen from the 

 oxyhemoglobin, can we perceive any physical action which 

 would, in the first place, perform the work of dissociation, and 

 then present the oxygen to the tissues in a form in which they 

 would readily take it up ? Ernst Fleischl von Marxow holds that 

 he has discovered such an action or agency in the stroke of the 

 heart. He founds his theory on some remarkable experiments, 

 which may be readily repeated with an ordinary tight-fitting 

 hypodermic syringe. (1) Immerse the syringe wholly in water, 

 so as to exclude air. Place one finger over the nozzle, draw up 

 the piston for about half the length of the syringe, and then 

 suddenly remove the finger from the nozzle. The water will rush 

 in, and gas will be given off in considerable amount, the 

 water being quite frothy for a short time. This is what one 

 would expect. (2) Then carefully empty the syringe of air and 

 gently draw it half full of water ; then place the finger on the 

 nozzle and draw the piston up a little, so as to leave a vacuum 

 above the water. In these circumstances a few large bubbles of 

 gas will come off, but the water will not froth. (3) Empty the 

 syringe thoroughly, fill it half full of water, raise it obliquely so 

 that the knob at the end of the handle of the piston is above the 

 water, strike the knob sharply with a piece of wood, using the 

 latter as a mallet ; then draw the piston up a little, so as to 

 leave a vacuum above the fluid. You will now observe that so 

 large an amount of gas is given off as to cause the fluid to froth. 

 In this experiment, the percussion stroke has evidently altered 

 the mode in which the gas escapes when a vacuum has been 

 formed above it. These experiments may also be done by using 

 a long barometer tube, with a stop-cock at one end, and an 

 india-rubber tube communicating with a movable mercury 

 cistern (a bulb) at the other. By lowering and depressing the 

 bulb, a Torricellian vacuum may be formed, and water may be 

 admitted, as with the syringe. Of the effects of percussion, in 

 these circumscances, there can be no doubt, and the experiments 

 are extremely interesting from the physical point of view. 

 Fleischl von Marxow holds that when gases are dissolved in fluids 

 the condition is analogous to the solution of crystalloids. If a 

 fluid containing gas is shaken, more especially by a sudden sharp 

 stroke, the close connection between the molecules of the fluid 

 and of the gas is rent asunder, and the gas molecules lie outside 

 and between the molecules of fluid. A shock, therefore, con- 

 verts a real solution into a solution in which the fluid and 

 gaseous molecules are in juxtaposition ; and, if a vacuum is 

 formed soon after the stroke, small bubbles of gas make their 

 appearance more readily than if a stroke had not been given. 



He then applies this theory to the phenomena of the circulation 

 and of respiration. Starting with the query why the stroke of 

 the heart should be so sudden and violent, when a much slower 

 and more prolonged rhythmic movement would have been 

 sufficient to keep up the tension in the arterial system on which 

 the movement of the fluid depends, he boldly advances the 

 opinion that it serves for the separation of the gases. The blood 

 is kept in motion by a series of quick, sudden strokes, because, 

 for the taking up of the oxygen by the tissues, and the elimination 

 of carbonic acid by the lungs, it is not sufficient that the blood 

 runs steadily through the systemic and pulmonary circulations ; 

 and, therefore, a short, hard stroke is given to it immediately 

 before it enters the lungs and immediately after it has left the 

 lungs. These strokes liberate the gases from a state of solution, 

 and they become mixed with the fluid in a state of fine dispersion. 



This condition of fine dispersion is favourable for the elimination 

 cf the carbonic acid by the lungs, and for the using up of oxygen 

 by the tissues. 



Fleischl v6n Marxow then proceeds to state that loose chemical 

 combinations may also be dissolved by shocks, the gas passing 

 into a condition of fine molecular dispersion, and that a quick 

 repetition of the shocks prevents a recombination. As examples 

 of such loose combinations, he cites oxyhemoglobin and the 

 compounds of carbonic acid with the salts of the plasma. It is 

 here, in my opinion, that the theory fails, from want of experi- 

 mental evidence, There is no proof that shocks, such as those 

 of the contraction of the right and left ventricles, can liberate 

 gases from loose chemical combinations such as those with which 

 we have to deal, and it is somewhat strained to point to the 

 explosion of certain compounds excited by strong mechanical 

 shocks or by vibratory impulses. 



Some of the applications of the theory are very striking. For 

 example, Fleischl von Marxow suggests that asphyxia occurs 

 before the oxygen has disappeared from the blood, because it is 

 held by the haemoglobin so firmly that the tissues cannot obtain 

 it. Thus suppose no oxygen is admitted by respiration. It is 

 well known that all the blood in the body passes through the 

 heart and lungs in the time of one complete circulation — that is, 

 in about twenty seconds ; and we have it on the authority of 

 Pfliiger that in this time one-third of the oxygen is used up by the 

 tissues. According to the percussion theory, the stroke of the 

 left ventricle arterializes the blood — that is, liberates the oxygen 

 from the haemoglobin — and this arterialized blood is carried to the 

 tissues. The haemoglobin does not get sufficient time to recom- 

 bine with the oxygen, because of the successive strokes of the 

 heart and the vibrating thrill kept up in the arterial ramifications. 

 The free oxygen is used up by the tissues in the capillary circula- 

 tion, to the extent of one-third. After leaving the capillaries, the 

 two-thirds of oxygen again recombine with the haemoglobin, and 

 in this condition return to the heart, along with one-third of 

 haemoglobin that has lost its oxygen. In ordinary circumstances 

 this one-third would again obtain oxygen from the alveoli of the 

 lungs ; but if all the oxygen there has been used up, of course it 

 cannot obtain any oxygen. The blood flows from the lungs to 

 the left ventricle, when it is again arterialized, and again sent out 

 through the arteries ; but as there is now a large amount of free 

 hemoglobin present in the capillary circulation, it will seize hold 

 of a part of the oxygen, and the tissues will obtain less than the 

 usual supply. With each successive circulation, the amount of 

 oxygen available for the tissues will become less and less, until 

 the tissues receive none, because all the oxygen set free by each 

 beat of the left ventricle is seized hold of in the capillary circula- 

 tion by the reduced hemoglobin. The tissues die from want of 

 oxygen, because there is too much reduced hemoglobin present, 

 a substance having a greater affinity for oxygen than the tissues 

 possess, a result that would probably occur, as in drowning, in 

 the time of six or eight complete circulations — that is, in three or 

 four minutes. 



Time will not allow me to refer further to this ingenious 

 theory, which still requires the proof that such shocks as those 

 of the heart can liberate gases from the compounds that exist in 

 the blood. In my opinion, Fleischel von Marxow exaggerates 

 the importance of the shock, while he under-estimates the 

 evidence of the spectroscope, which always shows the spectrum 

 of oxyhemoglobin even in arterial blood drawn from the neigh- 

 bourhood of the heart, and kept from contact with the air. Nor 

 can I accept his statement that the force of the stroke of the 

 heart is practically the same in all classes of warm-blooded 

 animals, and one can hardly imagine the feeble stroke of the 

 left ventricle of a mouse would be sufficient to liberate the 

 oxygen from the oxyhemoglobin of its blood. Further, it may 

 be urged that the conditions of the experiments with the syringe 

 are very unlike those of the circulation, more especially in the 

 fact that the walls of the syringe are rigid, while those of the 

 heart and vessels are yielding and elastic Again, when an 

 organ is supplied with a solution of oxyhemoglobin from a 

 pressure bottle, by a process of transfusion, the tissues will 

 reduce the oxyhemoglobin, and take up the oxygen without any 

 kind of percussion action being brought into play. 



Physiologists, however, cannot but treat with the greatest 

 respect the experiments and reasoning of a physicist so able as 

 Fleischel von Marxow is known to be, and the theory will be 

 thoroughly tested in every detail. I may be allowed to contri- 

 bute an expression of deep interest in this brilliant speculation, 

 and to say that I entirely agree with its author in accepting the 

 suggestions of teleology in the investigations of such problems. 



