130 Journal of Comparative Neurology. 



Two things follow from this : First, that in both of these 

 species the female is in general the heavier — as we have seen to 

 be the case in our own R. virescens brachycephala — and second : 

 the influence of the heavier body of the female must be elimi- 

 nated before the relative development of the nervous system ac- 

 cording to sex can be stated. 



We have found both for the Bull-frog and for R. virescens 

 that " the relative weight of the brain and the spinal cord de- 

 creases as the body weight of the frog increases," Table I. in 

 the former paper and Table V. in this, may be here cited in 

 evidence. 



Let us now apply this correction to Fubini's results : 



For this purpose the table of Fubini based on the eviscer- 

 ated frogs can alone be used because when not eviscerated the 

 body weights of the females were rendered worthless for statis- 

 tical purposes by the presence of the ova. 



Fubini's table is given below. 



TABLE XIV. 



Species. Weight of Brain. Relative Weight of Body, 



Male. Female. 



R. temporaria I. 262 291 



R. esculenta i. 257 287 



The Table (XIV) is formed by dividing the average (evis- 

 cerated) body-weight by the weight of the brain, and hence, 

 expressed in milligrams, it means that one milligram of brain 

 is correlated in the first species with 262 milligrams of male 

 body and 291 milligrams of female body. 



Further, it shows that the number representing the body 

 weight is larger for the females than for the males, and hence 

 his conclusion that the females have proportionately the larger 

 body, or, expressed in another way, the smaller brain. 



To determine whether these ratios have any bearing on sex, 

 apart from body-weight — which happens to be greater in the 

 female — we select from Fubini's table (i. e. the table used to 

 give the ratio for the male of this species in the above table 

 XIV) of R. temporaria, the evicerated males. The three 

 smallest individuals give a body-weight of 14.9, 15.6 and 18. i 



