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THE AMERIt AN NATURALIST [Vol. XLIII 



The facts regarding- the sex relations in the weight of the 



interesting. Just as in man the brain of the male rat is abso- 

 lutely somewhat heavier than is that of the female rat of the 

 same body weight. The difference, however, is very small. It 

 is believed by Donaldson that this small difference which re- 

 mains in favor of the male in respect to brain weight is prob- 

 ably open to further reduction as other variables are taken into 

 account. In general the quantitative relations of the growth 

 of the central nervous system are found to be similar in man 

 and the white rat. 



A paper with very much the same general standpoint as the 

 one just discussed has recently been published by Kellicott. 3 

 The immediate problem with which this paper has to do is 

 stated in the following words (p. 319) : 



We are led to inquire whether the normal growth of an animal may 

 not be actually a complex of growth cycles of component parts. It 

 is quite possible to examine this question from the morphological as 

 well as from the physiological side and the present paper represents 

 an attempt to discover whether the brain and viscera of the dogfish 

 grow similarly or in diverse ways as somewhat independent units of 



The investigation is based on data obtained from a series of 

 315 dogfish (176 females. 139 males) including specimens from 

 birth up to those of large size and presumably considerable age 

 (maximum weight observed S.434 grams). On these fish the 

 weights of the following organs were determined: brain, heart, 

 rectal gland, pancreas, spleen, liver and gonad. In addition the 



were made in all cases except body weight to hundredths of a 



specimens, the whole of the material is dealt with "from the 

 standpoint of total body weight as a base. The author justifies 



The specimens studied do not represent a random sample of a 

 fish population, but were especially selected to get a represen- 



