Sept. 8, 1881] 



NATURE 



441 



aclually exist in the gas-pump) of separating the gaseous mixture 

 from the htiuid, and of renewing the vacuum, we should be able 

 to determine (l) the total quantity of gases which the blood 

 yields, and (2), by analysis, the proportion of eich gas. 



Now, with reference to the blood, by the application of the 

 " blood-pump," as it is called, we have learnt a great many facts 

 relating to the nature of respiratiDn, particularly that the differ- 

 ence of venous from arterial blood depends not on the presence 

 of "etfete matter," as u^ed to be thought, but on the less amount 

 of oxygen held by its coloiu-ing matter, and that the blood which 

 flows back to the heart from different organs, and at different 

 times, differs in the amount of oxygen and of carbonic acid gas 

 it yields, according to the activity of the chemical processes 

 which have their seat in the living tissues from which it flows.' 

 But this is not all that the blood- pump has done for us. By 

 applying it not merely to the blood, but to the tissues, we have 

 learnt that the doctrine of Lavoisier was wrong, not merely as 

 regards the place, but as regards the nature of the essential 

 process in respiration. The fundamental fact which is thus 

 brought to light is this, that although living tissues are constantly 

 and freely supplied with oxygen, and are in fact constantly 

 tearing it from the haemoglobin which holds it, yet they them- 

 selves yield no oxygen to the vacuum. In other words, the 

 oxygen which living protoplasm seizes upon with such energy 

 that the blood which flows by it is compelled to yield it up, 

 becomes so entnely part of the living material itself that it can- 

 not be separated even by the vacuum. It is in this way only 

 that we can understand the seeming paradox that the oxygen, 

 which is conveyed in abundance to every recess of our Ijodies by 

 the blood-sti'eam, is nowhere to be found. Notwithstanding 

 that no oxidation-product is formed, it becomes latent in every 

 bit of living protoplasm ; stored up in quantity proportional to 

 its potential activity — i.e. to the work, internal or external, it has 

 to do. 



Thus you see that the process of tissue respuation — in other 

 words, the relation of living protoplasm to oxygen — is very 

 different from what Mayer, who localised oxidation in the 

 capillaries, believed it to be. And this difference has a good 

 deal to do with the relation of Process to Product in muscle. 

 Let us now revert to the experiments on this subject which we 

 are to take as exemplification of the truth of Mayer's forecasts. 



The living muscle of a frog is placed in a closed chamber, 

 which is vacuous — i.e. contains only aqueous vapjtir. The 

 chamber is so arranged that the muscle can be made to contract 

 as often as necessary. At the end of a certain period it is found 

 that the chamber now contains carbonic acid gas in quantity 

 corresponding to the number of contractions the muscle has per- 

 formed. The water which it has also given off cannot of course 

 be estimated. Where do these two products come from ? The 

 answer is plain. The muscle has been linng all the time, for it 

 has been doing work, and {as we shall see immediately) pro- 

 ducing heat. What has it been living on ? Evidently on stored 

 material. If so, of what nature ? If we look for the answer 

 to the muscle, we shall find that it contains both proteid and 

 sugar-producing material, but which is expended in contraction 

 we are not informed. There is, however, a way out of the 

 difliculty. We have seen that the only chemical products which 

 are given off during contraction are carbonic acid gas and water. 

 It is clear, therefore, that the material on which it feeds must 

 be something which yields, «hen oxidised, these products, and 

 these only. The materials which are stored in muscle are 

 oxygen and sugar, or something resembling it in chemical 

 composition. 



And now we come to the last point I have to bring before you 

 in connection with this part of my subject. I have assumed up 

 to this moment that heat is always produced when a muscle does 

 work. Most people will be ready to admit as evidence of this, 

 the familiar fact that we warm oiu'selves by exertion. This is 

 in reality no proof at all. 



The proof is obtained when, a muscle being set to contract, 

 it is observed that at each contraction it becomes warmer. In 

 such an experiment, if the heat capacity of muscle is known, 

 the weight of the particular muscle, and the increase of tempera- 

 ture, we have the quantity of heat produced. 



If you determine these data in respect of a series of contrac- 

 tions, arranging the experiments so that the work done in each 

 contraction is measured, and immediately thereupon reconverted 

 into heat, the result gives you the total product of the oxidation 

 process in heat. 



' Luiwig's first important research on this subject was pullishid in 1S62. 



If you repeat the same experiment in such a way that the 



work done in each contraction is not so reconverted, the result 



is less by the quantity of heat corresponding to the work done. 



I The results of these two experiments have been found by Prof. 



, Fick to cover each other very exactly. I have stated them in a 



table' in which we have the realisation as regards a single 



muscle of the following forecast of Mayer's as reg,ards the whole 



■ animal organism. "Convert into heat," he said, "by friction 



; or otherw ise, the mechanical product yielded by an animal in a 



t given time, add thereto the heat produced in the body directly 



I dtiring the same period, and you will have the total quantity of 



I heat which corresponds to the chemical processes." We have 



I seen that this is realisable as regards muscle, but it is not even 



yet within reach of experimental verification as regards the 



whole animal. 



I now proceed abruptly (for the time at our disposal does not 

 admit of our spending it on transitions) to the consideration of 

 the other great question concerning vital motion, namely the 

 question how the actions of the muscles of an animal are so 

 regulated and co ordinated as to determine the combined move- 

 ments, whether rhythmical or voluntary, of the whole body. 



As every one knows who has read the "Lay Sermons," the 

 nature and meaning of these often unintentional but always 

 adapted motions, which constitute so large a part of our bodily 

 activity, was understood by Descartes early in the seventeenth 

 century. Without saying anything as to his direct influence on 

 his contemporaries and successors, there can be no doubt that 

 the appearance of Descartes was coincident with a great epoch — 

 an epoch of great men and great achievements in the acquirement 

 of man's intellectual mastery over nature. When he interpreted 

 the unconscious closing of the eyelids on the approach of 

 external objects, the acts of coughing, sneezing, and the like as 

 mechanical and reflected processes, he neither knew in what part 

 of the nervous system the mechanisms concerned were situated, 

 nor how thev acted.- It was not until a hundred years after 

 that Whytt and Hales made the fundamental experiments on 

 beheaded frogs, by which they showed that the involuntary 

 motions which such prep.irations execute cease when the whole of 

 the spinal cord is destroved— that if the back part of the cord is 

 destroyed, the motions of the hind limbs, if the fore part, those 

 of the fore limbs cease. It was in 1751 that Dr. Whytt pub- 

 lished in Edinburgh his work on the involuntary motions of 

 animals. After this the next great step wxs made within the 

 recollection of living physiologists : a period to which, as it 

 coincided with the event which we are now commemorating— 

 the origin of the British Association— I will now ask yourspecial 

 attention. , „ tt n- • j 



Exactly forty-nine vears ago Dr. Marshall Hall communicated 

 to the Zoological Socletv of London the first account <^ h'* ex- 

 periments on the reflex function of the spinal cord. The facts 

 which he had observed, and the conclusions he drew from them, 

 were entirely new to him, and entirely new to the physiologists 

 to whom his communication was addressed. Nor can there be 

 any reason why the anticipation of his fundamental discovery by 

 Dr. Whytt should be held to diminish his merit as an original 



■ Relation) of Proditct and Process in Muscle 



(Result of one of Pick's experiments) 



Mechanical product 6670 granimemillimeters. 



Its heat-value 



Heat produced 



Total product reckoned as hea. ... -■-■-.. ■■ • . ,. ,v 



s Descartes- scheme of the central nervous mechanism comprised all the 

 parts which we now regard 2 



J5"6 milligrammeunits. 



39-0 



546 

 . mectu 

 eflex-action." Sensory nerves 



•enresented by threads (filets) which connected all parts of the body 1 

 am (" CEuvres," par V. Cousin, vol. iv. p. 359) ; ""Ot""- n=,7« \Y <"'" 



the brain ( , ^ - -, 



which extended from the brain to the muscles : ...oiu. ..,.....^0 .., r-— - 

 which were arranged on the internal surface of the ventricular cavity of the 



brain and guardid the entrances - ••■- "■ ''" ^'"^ ""'^ ^''^ 



supposed to be kepi 

 it from the heart by 



by "pores" 

 ivity of th 

 =..„«...^, - the motor tubes. This cavity wa 

 tantly charged with " animal spirits furnished to 

 e ncan uy iuiei.es specially destined for the purpose. Any " mci- 

 f the surface of the body by an external object which affects the 

 organs of sense does so, according to Descartes, by producmg a motion at 

 "hISed Pt. This is communicated to the pore by the thread and causes 

 it to open, the co.nsequence of whichjs that the" ammal sprit "^^contained in 



iiic vcuincular'cavity eaters the tube and is conveyed by it 

 muscFes with which It is connected , so as to produce the appropriate . 

 Thlwhole system, although.it was paced under the superv,s.on of the 

 "^«ifroKOT<iWf" which had its office in the pinea gland, was capable ot 



ihe absence of fact basis. Neither threads nor pores nor tubes lia\e an> 

 existence. 



