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THE AMERICAN NATURALIST [Vol. XLIII 



parts of the soma give out to the blood specific chemical substances 

 which have a marked effect on development, and in presence of which 

 the gametes develop. If we suppose that certain parts, e. g., the 

 frontal periosteum in the ancestors of deer, are stimulated to hyper- 

 trophy by external stimulation, this entails an increase in the hormone 

 produced by this part of the body, and this hormone will affect the 

 protoplasm of the gametes which obtain their nourishment from the 

 blood. Mendelians and the majority of modern authorities on heredity 

 and evolution assume that certain material parts of the gametes corre- 

 spond and determine particular parts and characters of the soma, and 

 therefore the hormones derived from these parts of the soma may well 

 have an influence on the corresponding determinants in the gametes. 

 ... I must of course assume different hormones for different bones 



modification of the determinant corresponding to that bone, not of 

 bone in general. Thus we have a material chain of influence from a 

 particular part of the soma to the gamete, and from the latter to the 

 corresponding part in the next generation. Whether this suggestion 



a conception of the means by which a change in the soma can effect 

 a corresponding part in the descendant. The hypothesis I have sug- 

 gested would explain ordinary adaptations more easily than secondary 

 sexual characters. It might be applied, for instance, to the hoofs, toes 

 and legs of Ungulata. 1 hope soon to test my hypothesis by physio- 

 logical experiment. If there is an influence from the parts of the 



animal -rafted into another, ought to show an alteration in the char- 



The author has apparently not seen an account of Guthrie's 

 work of grafting ovaries. However, it is far from certain, or 

 believable, that specific hormones are given off when the head 

 is rubbed, wdiich affect specific determinants in the germ which 

 cause that specific part of the head to hypertrophy in the next 

 generation in the special sex corresponding to the germ whose 

 containing soma had its head rubbed. Doubtless there are those 

 who would consider this to be complicated pangenesis worse com- 

 plicated. There seems to be a further point consistently ignored 

 by adherents to such a theory. They point out that only those 

 animals have horns which fight by hutting and believe that this 

 proves that horns are developed by butting. They imply that 

 if horses fought by butting they would develop horns; but it 

 seems rather likely, on the other hand, that if horses had horns 

 they would fight by butting. Cunningham, himself, quotes 

 Rorig to the effect that stags with no antlers guard the females, 



