V 



XVII 



HAS THE CENTRAL NERVOUS SYSTEM ANY INFLU- 

 ENCE UPON THE METAMORPHOSIS OF LARVAE? 1 



GUSTAV TOENIER has just published a hypothesis which 

 is to explain how the acquired characteristics of parents are 

 inherited by their offspring. This hypothesis is as follows: 



In the more highly organized animals every adaptation of a 

 functioning peripheral end -organ is accompanied by a corresponding 

 and equal adaptation in the central nervous system ; the central ner- 

 vous system carries the acquired characteristic to the sexual organ, 

 which forms with it a functional and nutritive unit, especially to 

 the sexual cells, in that it compels the latter to undergo similar 

 transformations. If the sexual cells give rise to new individuals, 

 the descendants inherit the acquired characteristics of the parents. 2 



Tornier's paper is very clear, and even though I cannot 

 agree with his hypothesis, I consider it important that 

 Tornier through his precise presentation of his subject has 

 directed the attention of investigators to the question of the 

 significance of the central nervous system in the processes 

 of development. 



If Tornier's idea is correct, then every alteration in the 

 central nervous system must be accompanied by a similar 

 change in the end-organs. Before the appearance of Tornier's 

 paper I had already made a series of experiments in which 

 I divided the spinal chord of Amblystoma larvae in order to 

 determine whether in the change of the Iarva3 to the sexually 

 mature form the animals with the divided spinal cord would 

 behave as one or two separate animals; in other words, 

 whether in an animal with a divided spinal cord the meta- 

 morphosis of the /nterior and the posterior portions would 

 occur simultaneously as in the case of the uninjured animal. 



i Archiv filr Entwickelungsmechanik der Organismen, Vol. IV (1896), p. 502. 

 2"tfber Hyperdaktylie," etc., ibid., Vol. Ill, p. 180. 



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