March 23, 1893 



NATURE 



491 



overcame all such scruples, and the plastic exudations were 

 received as undoubted evidence that fibrin possessed the power 

 of becoming organised. They formed, in the crasis doctrine of 

 the Vienna school, the bright spot of this newest kind of htemato- 

 pathology. 



Wherever fibrin failed, blastemata were brought to the fore. 

 Ever since Schwann had given the name of cytoblastema to the 

 organising material of the egg, the way had been open for 

 assuming in other places the existence of material with this 

 ambiguous name. 



But of course through these steps the one simple matter of life 

 predicated by Hunter was replaced by many " matters of life," 

 and thus the entire advantage gained by the exposition of a 

 unitary theory of life was at once lost. 



Even when, finally, the cell-contents were designated as pro- 

 toplasm, and thus the one requisite of Hunter, namely, that the 

 material of life mu>t also be contained in the individual parts, 

 appeared to be fulfilled, yet no single specific material was 

 thereby arrived at. No one dreamed of regarding protoplasm 

 as fibrin, and least of all did any one consider it a simple 

 chemical body. 



By the conception of the blastema, however, there had been 

 reawakened a thought which had occupied the minds of man from 

 the earliest times. If a plastic matter capable of being organised 

 really existed in the body, then the organisation of the same 

 must present the first reliable example of epigenesis. The 

 problem of the " generatio sequivoca," which had been fought 

 over for so long a time, now appeared to be solved. What 

 Harvey had taught concerning the continuous descent from the 

 egg became temporarily obliterated, when the theory of descent 

 through exudation made its appearance. Several generations of 

 young medical men have been educated in this belief. I myself 

 remember my " epigenetic " youth, with no little regret, and I 

 have had hard work to force my way through to the recognition 

 of the sober truth. 



Meanwhile, the attention of other bodies of inquirers had been 

 directed to the tissues of the body. Among these, in view of 

 their importance, the nervous tissues, and especially the mass of 

 nervous tissues in the brain and spinal cord, rank highest. 



Hunter also had acknowledged the importance of the brain, 

 and hence called it the "materia vitae coacervata." It was 

 easily seen that it contained no fibrin, but experimental re- 

 search showed also that neither the brain nor the spinal cord 

 was of the same value throughout all its parts. The more 

 accurate the experiments the smaller became the region which, 

 in the strictest sense, is the vital part, until Flourens limited it 

 to one single spot, the knot of life ("nceud vital "). Was the 

 unity of life found in this way ? By no means. The brain is 

 no more and no less vital than the heart ; for life is present in 

 the egg long before the brain and heart are formed, and all 

 plants, together with an immense number of animals, possess 

 neither the one nor the other. In the highly compound organ- 

 ism of man, the brain and spinal cord have a certain determin- 

 ing action on other parts necessary to life. Their disturbance 

 may immediately be followed by the disturbance of other vital 

 organs, and sudden death may ensue. 



But the collective death of a compound animal no more 

 implies the immediate local death of all its special parts than 

 the local death of some of the latter is incompatible with the 

 continued collective life of the animal. As has been well said, 

 at the death of a compound organism there is a " primum 

 moriens," one part which first ceases to live ; then follow, at 

 long intervals sometimes, the other organs, one after the other, 

 up to the "ultimum moriens." Hours and days may pass be- 

 tween the total death of the individual and the local death of 

 the parts. The fewer nerves a part contains the more slowly 

 usually does it die ; I therefore consider the process of dying in 

 the compound organism as the best illustration of the individual 

 life of the several constituent parts, which is in its turn the first 

 axioma necessary for the study and for the understanding of 

 life. 



A long time, however, elapsed before it was possible to re- 

 turn to this starting point, and to obtain a considerable number 

 of supporters for the doctrine of the "vita propria." The at- 

 tention of many observers was drawn to a totally different side 

 of the question. In the last decade of the past century, about 

 the same time that John Hunter, starting from careful anatomi- 

 cal investigations and exact observations of surgical practice, 

 worked out his idea of the material of life, a new system of 

 medicine was founded in Scotland, the so-called Brownian system, 



NO. 1221, VOL. 47] 



which was based on quite different premisses. Brown also 

 was a vitalist ; he, too, constructed, not merely a patho- 

 logical and therapeutic system of vitalism, but a physio- 

 logical one, though this doctrine was dynamic in its character. 

 There is but little to be noticed therein of the material anato- 

 mical foundation of exact medicine. It is concerned principally 

 with contemplations of the forces of the living organism. One 

 can understand to some extent how this happened, if one keeps 

 in view the histo.y of the development of this extraordinary 

 personality ; I cannot go into this here, but anyhow the remark- 

 able fact remains that the two contemporaries. Brown and Hun- 

 ter, worked near each other without its appearinij from their 

 writings that they were acquainted with one another. Brown 

 struck out his own line, and stuck to it, without troubling 

 himself about the rest of the medical world. And yet even his 

 first work " Elementa Medicinaj," had the eft'ect of an earth- 

 quake ; the whole European continent was shaken by it, and 

 even the physicians of the recently opened New World bent under 

 the yoke of revolutionary ideas ; and in a few years the aspect 

 of the whole field of medicine was entirely changed. True ! 

 the triumph was but short ; the Brownian system disappeared 

 as it had come, a meteor in the starry heaven of science. There 

 would be no reason to go into it more fully, had not the impulse 

 which he had given instigated other men, and be permanently 

 applied by them to the true service of science. This impulse 

 was founded on the fact that irritability, or, as Brown called it, 

 "incitability," was thus reinstated as the starting point of the 

 theory ; but, along with this, the stimuli which set living sub- 

 stances in action, the " potestates incitantes," were brought to 

 the fore. In so far that stimuli produce a slate of irrita'ion 

 (" incitatio"), or, as Brown called it later, excitement, they 

 came to be viewed not only as the cause of health and disease, 

 but even of life itself ; for excitement, so he said, is the true 

 cause of life. But, as excitement stands in a certain relation to 

 the strength of the stimulus, a state of good health was only 

 possible with a normal degree of stimulus, whilst an e.xcess or a 

 lack of stimulus brought diseased conditions in its wake. Of 

 course excitement is dependent also on irritability, with a certain 

 quantity of which, in the form of energy, every living being is 

 endowed at the beginning of its life. 



The division of diseases, according to the amount of vital 

 force visible in them, into sthenic and asthenic, has never been 

 abandoned since, though acknowledged perhaps in a less precise 

 manner ; it has sometimes been brought more prominently 

 forward, and sometimes thrown into the background. In 

 Germany, Schonlein was the one of all others who took this 

 doctrine as the foundation of his opinion on special cases of 

 disease, and for his choice of treatment. 



But the application of the Brownian principles to physiology 

 has been of far greater importance. If life itself were depen- 

 dent on external stimuli, the notion of the spontaneity of vital 

 actions, a notion still in force, must lose all significance. Certain 

 stimuli would in that case prove to be necessary conditions of 

 vital activity, without which life could at best be carried on in a 

 latent form only. Certainly even for this latent life the question 

 remained open : How does it come to pass, and in what does it 

 practically consist ? Brown avoided this ticklish question, not 

 without great skill, by drawing the whole attention to active 

 life and to the stimuli which call forth action. To speak openly, 

 science has since then deflected little, or not at all, from this 

 guiding notion. Even now, we cannot say what latent life is. 

 We simply know that through external stimuli it may be con- 

 verted into active life, and hence irritability is considered by us 

 as the surest sign of life, not of course of the general life of all 

 matter in the sense of Glisson, but of the real and individual life 

 of special living organisms. Brown remarked, with reason, that 

 through irritability the living substance is differentiated from the 

 same substance in its dead condition, or from any other lifeless 

 matter. Nevertheless, neither irritability nor incitability, 

 neither irritation nor incitation, explains the essence of the living 

 substance, and therefore neither explains the essence of life. 



In Germany the physiologists especially took up this question. 

 Among the first was Alexander von Humboldt, who in his 

 various writings, especially in his celebrated treatise on the 

 irritated muscle and nerve fibre, entered into the question. In 

 the end he held fast to the assumption of a vital force. The 

 majority of pathologists and physicians followed in his footsteps, 

 and long and fierce controversies were necessary before, nearly 

 half a century later, the belief in a vital force was destroyed. 

 When du Bois-Reymond had demonstrated the electrical current 



