124 



Prof. Rudolf Virchow. The Position of [Alar. 16. 



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 re- 

 awakened a thought which had occupied men's minds 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 

 aBquivoca," so long fought over, 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 research showed also that 

 neither the brain nor the spinal cord was of the same value through- 

 out all its parts. The more accurate the experiments, the smaller 

 became the region which, in the strictest sense, is the vital part, until 

 Elourens 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 organism of man, the 

 brain and spinal cord have a certain determining 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, sometimes at long intervals, the other organs, one after the 

 other, up to the " ultimum moriens." Hours and days may pass 

 between 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 



