Ill] OF PARTS OR ORGANS 187 



good throughout life, between the size of the body and its organs; 

 and the ratio of magnitude tends to change not only as the individual 

 grows, but also with change of bodily size from one individual, one 

 race, one species to another. In giant and pigmy breeds of rabbits, 

 the organs have by no means the same ratio to the body- weight ; but 

 if we choose individuals of the same weight, then the ratios tend to 

 be identical, irrespective of breed*. The larger breeds of dogs are 

 for the most part lighter and slenderer than the small, and the organs 

 change their proportions with their size. The spleen keeps pace 

 with the weight of the body ; but the liver, hke the brain, becomes 

 relatively less. It falls from about 6 per cent, of the body-weight 

 in little dogs to rather over 2 per cent, in a great hound f. 



The changing ratio with increasing magnitude is especially 

 marked in the case of the brain, which constitutes (as we have just 

 seen) an eighth of the body- weight at birth, and but one-fiftieth at 

 twenty-five. This faUing ratio finds its parallel in comparative 

 anatomy, in the general law that the larger the animal the smaller 

 (relatively) is the brain J. A falhng ratio of brain- weight during life 

 is seen in other animals. Max Weber § tells us that in the lion, at 

 five weeks, four months, eleven months and lastly when full-grown, 

 the brain represents the following fractions of the weight of the body : 

 viz. i/18, 1/80, 1/184 and 1/546. And Kellicott has shewn that in the 

 dogfish, while certain organs, e.g. pancreas and rectal gland, grow 

 pari passu with the body, the brain grows in a diminishing ratio, 

 to be represented (roughly) by a logarithmic curve ||. 



In the grown man, Raymond Pearl has shewn brain-weight to 

 increase with the stature of the indix'idual and to decrease with 

 his age, both in a straight-hne ratio, or linear regression, as the 



* R. C. Robb, Hereditary size-limitation in the rabbit, Journ. Exp. Biol, vi, 

 1929. 



t Cf. H. Vorsteher, Einfiuss d. Gesamtgrosse auf die Zusammensetzung des 

 Kbrpers; Diss., Leipzig, 1923. 



X Oliver Goldsmith argues in his Animated Nature as follows, regarding the un- 

 likelihood of dwarfs or giants: "Had man been born a dwarf, he could not have 

 been a reasonable creature; for to that end, he must have a jolt head, and then he 

 would not have body and blood enough to supply his brain with spirits; or if he 

 had a small head, proportionable to his body, there would not be brain enough for 

 conducting life. But it is still worse with giants, etc." 



§ Die Sdugethiere, p. 117. 



II Amer. Journ. of Anatomy, viii, pp. 319-353, 1908. 



