. ARE ACQUIRED CHARACTERS HEREDITARY? 345 



adrenals and thyroids, will retard the growth rate, render the entire 

 organism albinous, and produce in the individual pigment cells a con- 

 dition of sustained contraction. Shall we conclude that such a far- 

 reaching influence as this, particularly in a developing organism, will 

 pass the germ-cells by unscathed ? 



Similarly, growth in man is known to be controlled by a pituitary 

 secretion that is carried by the blood to the various organs. The 

 normal development of secondary sexual characters is determined by 

 products from the testes or ovaries, and the activities of the generative 

 organs themselves are ultimately associated with the functioning of the 

 adrenal and other glands. The periods of ovulation are inhibited by 

 secretions from the corpus luteum; lactation is incited by products of 

 the corpus luteum, the involuting uterus and the placenta; the car- 

 bohydrate metabolism in the liver and even in the most distant 

 muscles is profoundly influenced by substances formed in the pan- 

 creas; the pancreas, liver, and intestinal glands are set to secreting 

 through the stimulus of a product formed in the duodenal and jejunal 

 mucosae. And still others of such remarkable interrelations can 

 be cited. 



Truly one may pronounce that social complex of reciprocating 

 individuals termed cells which make up an organism, "members one 

 of another." And with all of these co-operative activities of the 

 various parts of the body it is inconceivable to me, at least, that the 

 germ-cells, bathed in the same fluid, nourished with the same food, 

 stand wholly apart. 



May we not surmise then that as regards inheritance and evolu- 

 tion, Lamarck was not wholly in error when he stressed the importance 

 of use and disuse of a part, or of modifications due to environmental 

 change, in altering the course of the hereditary stream, particularly 

 if we conceive of these influences as being prolonged, possibly over 

 many generations ? Have we not in the serological mechanism of the 

 body of animals an adequate means for the incitement of the germinal 

 changes which underly certain aspects of evolution ? 



