Posthumous Action of the Nucleus 



57 



sive, which the nucleus was exerting at the moment of its 

 excision or shortly before. 



We can suppose, as we shall see better later, that this 

 posthumous action of the nucleus ("Nachwirkung") may 

 be explained in the following way : Each of the different 

 nervous currents which the nucleus can discharge simul- 

 taneously or successively into the protoplasm deposits in 

 it, of all the nuclear substances just that one which had 

 given origin to it, perhaps by reproducing it partially 

 while on its way. This substance once deposited in the 

 protoplasm, would act as a reserve which, while incapable 

 of growth by itself because it lies outside the nucleus, 

 would nevertheless preserve for a time, until its gradual 

 exhaustion, the capacity of producing the same current 

 again. It would produce in relation to the excision of the 

 nucleus, the same effect as would be produced by a very 

 slow propagation of the respective current through the 

 protoplasm. 31 



Therefore one can easily understand how in Gruber's 

 experiment, in which the adoral ciliated zone of the an- 

 imal was already in an advanced stage of formation, the 

 whole series of simultaneous or successive formative 

 stimuli had been already discharged shortly before the 

 excision of the nucleus, and that therefore it remained 

 only to await the slow unfolding of their effects, which 

 would bring to completion the development already far 

 advanced. 



"Compare the partly similar, partly different hypothesis of Ver- 

 worn on the posthumous action ("Nachwirkung") of the nucleus, 

 which may be attributed to a reserve material built up gradually 

 by the nucleus and given off to the protoplasm, and persisting till 

 the protoplasm is used up, in the above mentioned article: Die phy- 

 siologische Bedeutung des Zellkerns, P. 90; also: Die Bewegung 

 der lebendigen Substanz. Jena, Fischer. 1892. 



