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Prof. Kudolf Virchow. The Position of [Mar. 16, 



nevertheless, into the same by-path, into which, even in the most re- 

 cent times, so mStny learned men and even excellent observers have been 

 misled. This is the path of unlimited generalisation. The human 

 mind is only too prone to render intelligible what is unintelligible in 

 particular phenomena, by generalising them. Just as even in recent 

 times an attempt has been made to render consciousness intelligible by 

 representing it as merely a general property of matter, so Glisson 

 thought he might attribute to the active principle (" principium 

 energeticum ") which according to him is contained in all matter, the 

 three faculties of living matter which he considered as fundamental, 

 namely, the facultas perceptiva, appetitiva et motiva. All matter 

 was sensitive, was thus stimulated to develop impulses, and moved 

 itself as a consequence of these impulses. 



It is not necessary for the purpose of our present enquiry to carry 

 these quotations further, since they are quite, in the Paracelsian 

 sense, contemplative in their nature ; and especially as, in their 

 generalisation, they do not appear to be important for the history of 

 advancing knowledge. 



That which is full of significance for us is concerned with actual 

 life only, in the narrower sense of analytic science. It was not the 

 " principium energeticum " set up by Glisson, which stimulated his 

 successors again to take up the thread of his observations, but rather 

 this process of irritation described by him, together with the 

 fundamental faculties of living matter on which it depended. In 

 this way he has really led up to a more exact study of the actions of 

 life and the properties of living matter. 



Unfortunately, there intervened a mistaken conception, which led 

 his followers again into a series of most serious errors. Glisson, fol- 

 lowing on this point also the example of Van Helmont, was convinced 

 that nerves contracted when irritated. He added to this the idea 

 that, through the contraction of the nerves, or even of the brain, the 

 fluid contained in them was propelled towards the periphery. 



This notion, shared by Willis and many other physicians of that 

 time, furnishes the reason why irritability was identified with con- 

 tractility. Even the great master Hermann Boerhaave, and after 

 him his pupil Gaubius, the first special writer on general pathology, 

 considered sensation and motion as common properties of, at all 

 events, all the solid parts of the body. The former thought it 

 proved that hardly a single particle of the body existed which was 

 not sensitive and did not move ; and thus it becomes compre- 

 hensible how Haller himself carried this idea, that irritability had 

 the same significance as contractility, from his school days in Leyden 

 to his professorship in Gottingen. It was in this sense that he 

 understood the irritability of the muscles, and in the same sense he 

 denied this property to the nerves. 



