Januaky 21, 1910] 



SCIENCE 



99 



secretin formed in the plyorie mucous 

 membrane which gives rise to the chemical 

 secretion of gastric juice; a secretin 

 formed in the duodenal epithelium which 

 stimulates the formation of intestinal juice 

 in the following segments of the intestine ; 

 unknown hormones of pancreatic origin 

 which determine the absorption activity of 

 the intestinal epithelium; vaso-dilator hor- 

 mones formed in tissues in functional ac- 

 tivity and which have a specific effect upon 

 the vessels of the functioning organ; a 

 vaso-constricting and a diuretic hormone 

 formed in the posterior lobe of the pitui- 

 tary body; a hormone controlling the 

 growth of the bones and connective tissues 

 produced in the anterior lobe of the pitui- 

 tary body; a hormone controlling the oxi- 

 dation of sugar in the body and produced 

 in the cells of the islands of Langerhans 

 in the pancreas; a hormone produced in 

 the thymus which controls possibly in 

 some way the development of the repro- 

 ductive organs; a vaso-constricting hor- 

 mone formed in the kidneys ; a hormone in 

 the salivary glands which controls the 

 flow of water from the blood capillaries in 

 the glands; a hormone produced in the 

 foetus in utero which stimulates the 

 growth of the mammary glands; a hor- 

 mone in the ovary which controls the 

 growth of the uterus and the processes of 

 menstruation; a hormone in the ovary 

 which controls the implantation of the 

 fertilized ovum and the growth of placental 

 tissue ; a hormone in the testis which initi- 

 ates the development of the secondary 

 sexual characteristics in the male; hor- 

 mones of an indefinite number, produced 

 in all the tissues and acting specifically 

 upon the determinants in the gametes in 

 such a way as to make possible the trans- 

 mission of acquired characteristics. It is 

 evident from this summary that there is a 

 well developed tendency in physiology at 



the present day to utilize the conception of 

 hormones to explain all relationships not 

 otherwise intelligible. A few years ago the 

 number of hypothetical enzymes in the 

 body was likely to be increased whenever 

 a new research in metabolism appeared, 

 now the drift seems to be in the direction 

 of manufacturing new hormones. This 

 natural inclination to abuse a new and at- 

 tractive idea will not of course prejudice 

 us against the great importance of the sug- 

 gestion which we owe to Bayliss and Star- 

 ling. It is to be hoped only that no one 

 will be tempted to give to these hypothet- 

 ical hormones distinctive names, except in 

 cases such as the secretin, adrenalin, etc., 

 in which the substances have been isolated 

 in some degree of purity. For once a specific 

 name has become attached to an entirely un- 

 known substance it acquires henceforth an 

 easy currency in our literature, and soon 

 many of us unconsciously assume that the 

 thing so designated constitutes one of the 

 verified facts of our science. By way of 

 example one may cite the thrombokinase 

 which has become such a familiar term in 

 the literature of coagulation and which 

 not infrequently is employed by writers as 

 though its existence were a settled fact. 



Among his other valuable suggestions 

 regarding the characteristics of the hor- 

 mones, Starling has called attention to the 

 fact that some of them act by increasing 

 the processes of disassimilation or cata- 

 bolism, while others apparently stimulate 

 the processes of assimilation or growth. 

 In this latter group we may include the 

 hormones of the anterior lobe of the pitui- 

 tary body, according to the present concep- 

 tion of the functions of that gland, and all 

 of the hormones of the reproductive cells. 

 These latter have in general what has been 

 designated as a dynamogenic action, they 

 cause hypertrophies in various organs or 

 tissues and invoke therefore processes of 



