Herrick, Physiological Corollmies of Equilibrium Theory. 27 



the restoration of mutilations. When the newt's foot is ampu- 

 tated, under favorable circumstances the organ is quickly repro- 

 duced and the parts so restored differ in no obvious way from 

 the old organ removed. What is the power which causes such 

 a miraculous change ? Does it take place because a simulacrum 

 of the missing limb exists in the soul and the new body devel- 

 ops to correspond ? With due allowance for use of terms, we 

 reply, "yes, such a simulacrum does exist." The form of the 

 central equilibrium has been determined by constant reactions 

 between the member and the central system and when the mem- 

 ber is lost the equilibrium so established is still in force and the 

 nervous stimuli .which but lately served to supply tone to the 

 limb now operate upon the stump. Intense irritation results 

 and the tendency is to influence growth at the point of injury.^ 

 This growth is under the directive control of the nerve just as 

 we know the normal growth constantly to be. If the nerve of 

 the limb be injured beyond repair monstrous growth results. 

 It may be assumed that in case the leg were amputated and the 

 nerve destroyed in the stump above, that the efforts at restora- 

 tion might be abortive or result in monstrosities. It would be 

 well to test this matter experimentally. It is believed that the 

 application of the ideas indicated in this paper to the higher 

 spheres of nervous activity will prove fruitful. 



Another application of the same principle is found in the 

 processes connected with the regeneration of severed nerves. 

 It is a well authenticated fact that, in the case of section of a 

 peripheral nerve, the nuclei of the sheath of Schwann pass to 

 the centre of the lumen and form the protoplasmic prota of the 

 segments of the new nerve — a process wholly unintelligible if 

 we agree with KoUiker in regarding the sheath nuclei as derived 

 from non-nervous connective tissue corpuscles, but not so re- 

 markable if the abundant evidence be accepted that these nuclei 

 are but the diverted nuclei of the cells which formed the nerve 



1 The assumption that irritation may produce proliferation is supported by 

 the pathological karyokinesis in case of local irritation ; see also processes con- 

 nected with development of spermatozoids, etc. 



