280 Proceedings of the Royal Society of Victoria. 



it rises to 160, and in mankind remains at about the same value. 



This increase in the value of n as nerve development pro- 

 gresses, is a ready corollary from Von Baer's law, but many 

 difficulties arise in the attempt to work out the relation in a 

 general way. 



One may almost risk the prediction that the laws above 

 stated will be found to combine in this fashion : — 



I. — Reckoning / to be the time from the fusion of the nuclei 

 to some definite point in development, say, the capacity of the 

 young animal to stand, walk or swim ; T to be the temperature 

 at which development takes place, and w to be the weight of 

 the mature animal. Then as a first approximation 



k\'w 



T being reckoned from a definite point ; not necessarily any of 

 the recognised zeros. 



II. — But the quantity / tends decidely to increase with 

 increase of nerve complexity, as gauged by size and efficiency of 

 brain. 



