62 Traces of Unity in the 



chorda dorsalis, and how the two traberculae enclosing 

 the pituitary space may be none other than the homo- 

 logues of the two lateral halves of the body of the ver- 

 tebra in the stage prior to coalescence, This is an in- 

 ference which may be drawn from the facts ; this, so far 

 as I can see, is the only inference which seems to be 

 justifiable or even permissible. 



And in favour of this inference collateral evidence 

 may easily be found in the construction of the cerebro- 

 spinal axis of the nervous system : and in the peculiar 

 relation which this part holds to the 'bodies' of the 

 vertebrae. Whatever may be the ultimate reason of this 

 conformity, it cannot be doubted that between these 

 major centres of the nervous system and the ' bodies ' 

 of the vertebrse, there is a very close connection ; and 

 inasmuch as the nervous and osseous systems agree in 

 that each system is composed of corresponding zones, it 

 may, without any very extravagant flight of fancy, be 

 supposed that the law of formation of the so-called 

 centre in one case may be the law of formation of the 

 so-called centre in the other case also. At all events, it 

 must be allowed that the result of bringing the nervous 

 and osseous systems together with a view to observe 

 their parallelism is strangely confirmatory of the infer- 

 ence that has been made as to the nature of the ' bodies ' 

 of the vertebrae. The great cerebro-spinal so-called 

 centres are, not simple and central elements, but com- 

 posite structures produced by the more or less complete 

 coalescence of two lateral masses. The double nature 

 of the great neural axis is clear and unmistakeable. 

 And that the history of this axis is applicable to the 

 elucidation of the more obscure history of the bony 

 column is scarcely less clear and unmistakeable. It is 

 in the trunk, where the bodies of the vertebrse are most 



