Hatai, Weight of the Brain. 173 



As to the actual use of the above formula, I may add the follow- 

 ing remarks. 



As was mentioned already, the series reduces to 



<l> (log x) =.569 log (x-8.7) +0.554 



when (log x) is greater than 1 ; while, on the other hand, the series 

 reduces to 



yjj (log x) = 1.56 logx-.87 



when (log x) is less than 1. Therefore it is only necessary to note 

 whether we are treating rats in which the body weights are greater 

 or less than 10 grams. 



If the l)ody weight is greater than 10 grams, we can simply use 



<^ (log x) or y = .569 log (x- 8.7) +0.554 



and if it is less than 10 grams, the other formula 



\p (log X) or y = 1.56 log x - .87 



Of course, one can determine the brain weight directly from the 

 formula (8) after some laborious calculation; nevertheless such a 

 procedure has no advantage over the simpler process described above. 



The present formula (8) is desirable simply, first, because it is 

 free from the theoretical objections ; and, second, because by it we 

 can express the complicated relations existing between the body 

 and brain under a sinele generalized form. 



BIBLIOCxRAPHY. 

 Donaldson. H. H. 



1908. A comparison of the albino rat with man in respect to the 

 growth of the brain and of the spinal cord. ./. of Comp. 

 Neui-ol., vol. IS, no. 4. 

 1009. On the relation of the body length to the body weight and to 

 the weight of the brain and of the spinal cord in the albino 

 rat (Mus norvegicus var. albus). ,/. of Comp. Neurol, vol. 

 19, no. 2. 

 Hatai, S. 



1908. Preliminary note on the size and condition of the central 

 nervous system in albino rats experimenlally stunted. ,/. 0/ 

 Comp. Neurol. , vol. 18, no. 2. 



