June 30, 1922] 



SCIENCE 



689 



interrelationships that exist among the different 

 endocrine organs may explain why a disease 

 of the thyroid (exophthalmic goitre) may ap- 

 pear in one member of a family, a disease of 

 the pancreas (diabetes mellitus) in another, a 

 disease of the hypophysis (dystrophia adi- 

 posogenitalis) in a third, or a pluriglandular 

 disorder in a fourth member of the same fam- 

 ily. The experienced clinician can now often 

 recognize phenotypes in which there are 

 anomalies of constitution that predispose to 

 endocrine disorders; and as a result of this 

 recognition he may, sometimes, be able to insti- 

 tute a rational prophylaxis. The thyreotoxic 

 constitution, the hypothyreotic constitution, the 

 hypoparathyreotie constitution, the hyper- 

 pituitary constitution, the hypopituitary con- 

 stitution, the hypergenital constitution and the 

 hypogenital constitution are instances in point. 

 Unfortunately we have not learned as yet how 

 effectually to intervene in a prophylactic way 

 in all of these anomalies of constitution, but 

 rewarding experiences with the hypothyreotic 

 and with the hypoparathyreotie constitution 

 give us hope that, with widening knowledge, 

 suitable preventive measures will be discovered. 

 Studies of the symptoms of endocrine dis- 

 orders and studies of partial anomalies of con- 

 stitution affecting the endocrine organs are thus 

 throwing much light not only upon- (1) the 

 mode of action of the incretions, but also upon 

 (2) inheritance as a determining cause of endo- 

 crinopathic jDhenotypes. The incretions may 

 affect distant parts directly, being carried to 

 them by the blood; or they may affect those 

 parts indirectly through the intermediation of 

 the autonomic nervous system, which they sen- 

 sitize. When they act directly, they may influ- 

 ence the substances and processes in the locali- 

 ties that they reach (chemical correlation; reg- 

 ulation of metabolism) or they may supply 

 materials for incorporation by the cells (nutri- 

 tive and formative influences). When they 

 act indirectly through the vegetative nervous 

 system they may exert profound effects 

 through the secretory activity of glands, 

 through the contraction of smooth muscle, or 

 through modifications of those neural mechan- 

 isms that have to do with the emotions and 

 the will. During the developmental period, it 

 is clear that the incretions are in part responsi- 



ble for the dimensions and pix>portions of the 

 skeletal apparatus and the soft parts. A 

 normal functioning of the ineretory organs is 

 essential for the shaping of parts and for the 

 maturing of functions in the right place and 

 at the right time. Through correlative differ- 

 entiation (due in part at least to the action of 

 the incretions), the developing organism gradu- 

 ally comes to exhibit the characteristics of its 

 species, its age and its sex. Even the anthro- 

 pologists now maintain that the solution of 

 the problem of how mankind has been demar- 

 cated into types so diverse as the Negro, the 

 Mongol and the Caucasian will involve the 

 study of hormonic mechanisms ! 



CAN HORMONES MODIFY UNFERTILIZED GBKM- 

 CELLS SO AS TO INFLUENCE INHERITANCE 



Thus far in our discussion of the relation of 

 the endocrine glands to heredity and develop- 

 ment we have confined our attention to (1) 

 the genotypic determination of endocrine func- 

 tions in developing organisms, (2) the role 

 played by the incretions in normal and patho- 

 logical ontogeny, and (3) the fact that there 

 exist hei'edo-familial anomalies of body make- 

 up that predispose to endocrine disorders.. But 

 we must, for a few moments at least, consider 

 the possibility that hormones, reaching unfer- 

 tilized gsrm-cells, may modify the germ plasm 

 in such a way as to give rise to new inheritance 

 factors that will be transmitted from genera- 

 tion to generation. 



Experiments upon the influence of ineretory 

 substances upon the development of cold-blood- 

 ed animals have yielded such striking results 

 upon cells of the soma that many have won- 

 dered whether incretions circulating in the 

 blood might not also permanently alter the 

 germ-cells so as to account in animals for the 

 origin of mutations- and new biotypes. You 

 will recall the experiments to which I refer 

 (1) the acceleration of tadpole metamorphosis 

 by feeding thyroid substance and (2) the re- 

 tardation of the same process by feeding thy- 

 mus substance. 



In endocrine diseases of either endogenous 

 or exogenous origin, the cells of the soma are 

 also markedly altered; and the c|uestion has 

 naturally been asked. May not tlie germ-cells 

 be simultaneously profoundly changed? 



