INTERNAL SECRETIONS AND ACQUIRED 



CHARACTERS 



A Review 



Hormones and Heredity, by J. T. 

 Cunningham. Pp. xx + 246. 

 New York. The Macmillan Com- 

 pany. 1921. 



While the chief object of the volume 

 is, in the author's words, "to discuss 

 the relations of modern discoveries 

 concerning hormones or internal se- 

 cretions to the question of the evolu- 

 tion of adaptations, and on the other 

 hand to the results of recent investi- 

 gations of Mendelian heredity and 

 mutations," it reviews a wide range 

 of subjects, many of which are but 

 remotely if at all connected with 

 hormones. Thus, the following topics 

 are discussed : Historical Survey of 

 Theories or Suggestions of Chemical 

 Influences in Heredity ; Classification 

 and Adaptation ; Mendelism and the 

 Heredity of Sex; Influence of Hor- 

 mones in Development of Somatic 

 Sex-characters ; Origin of Somatic Sex- 

 characters in Evolution ; Mammalian 

 Sexual Characters ; Evidence Opposed 

 to the Hormone Theory; Origin of 

 Non-sexual Characters ; The Phenom- 

 ena of Mutation; Metamorphosis and 

 Recapitulation. 



From time to time throughout the 

 work an irascibility is evinced toward 

 Mendelism, but just why, one is un- 

 able to determine from any analysis 

 suljmitted in the text. The supposed 

 difficulties mentioned appear to the re- 

 viewer, at least, to be largely false 

 issues which are adequately accounted 

 for by the modern factorial hypotheses 

 of Neo-Mendelists. Various of the 

 other difficulties which are cited by the 

 author as outstanding, have been dis- 

 cussed and shown to be at least not 

 necessarily in disharmony with Men- 

 delism by Morgan, in his Heredity 

 and Sex, published in 1913 — a volume 

 with which Cunningham api)ears to 

 be unacquainted. 



The ])ook, in the main, is an elabora- 

 tion and defense of the author's earlier 

 Lamarckian theory of the origin of 

 secondary sexual characters in rela- 

 tion to hormones, although the theory 

 is extended to other adaptive structures 

 and to certain types of non-sexual 

 characters. His central idea appears 

 to be that any over- or under-produc- 

 tion of hormones may stimulate the 

 appropriate "determinants" in the 

 genital cells and modify them cor- 

 respondingly. The author avows his 

 adherence to the idea of continuous 

 variation (fluctuations) in the Darwin- 

 ian sense as distinguished from muta- 

 tions, but apparently his conception of 

 mutations is the older one which re- 

 gards them as changes of considerable 

 magnitude, rather than the modern one 

 which admits of any degree of minute- 

 ness. Recognizing as do all modern 

 naturalists that the origin of species 

 and the origin of adaptations respec- 

 tively are two distinct problems, he 

 attempts to account for the latter on 

 the basis of hormonic influences. 



In his own words : 



My view is, then, that specific characters 

 are usually not adaptations, that other char- 

 acters of taxonomic value are some adap- 

 tive and some unrelated to conditions of 

 life, and that while non-adaptive characters 

 are due to spontaneous blastogenic varia- 

 tions or mutations, adaptive characters are 

 due to the direct influence of stimuli, caus- 

 ing somatic modifications which become 

 hereditary, in other words, to the inheritance 

 of acquired characters. 



Since to do justice to the author's 

 ideas it seems safest to set them forth 

 in his own phraseology, the reviewer 

 has chosen the following representative 

 passages which indicate the trend of 

 the argument. 



The fact that a hormone from the testis 

 afi'ects the development of the antler, as well 

 as our knowledge of hormones in general, 



136 



