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 intimately 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 
changé, 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 ? 
