ACTIVATORS, KIN \- - \\ . / \ . > 



with this definite instance furnished by the secretin, 

 aval Starling's convenient term of "hormone," as a general 

 designation for such substances, has served to give a wide 



.ley to the conception. The word and the generaliza- 

 tion implied by it have been adopted by investigators in 

 many fields of biological research to explain phenomena of 

 correlation which heretofore it has been impossible to 

 bring under the general rubric of nervous reflexes; phe- 

 nomena which iu fact it has been difficult to express clearly 

 in any precise way such as might serve to stimulate direct 

 experimental investigation. An interesting example of 

 this application of the term and the idea contained iu it is 

 found in the theory advanced by Cunningham to explain 

 the development and inheritance of secondary sexual char- 

 acteristics. This author constructs * system of hypothe- 

 tical hormones which, if present, would account not only 

 for the development of the secondary sexual characters, 

 as the result of the actiou of specific hormones furnished by 

 the reproductive cells, but would also make conceivable a 

 met hod by which these secondary characters, like other 

 somato^cnic characters, mi^ht aft'evt the germ cells in turn 

 in snch a definite way as to be transmitted to the following 

 ireneratioiis 1: j| not my purpose to criticue this or similar 

 J will doubt less SWYC * good purpose in 

 stimulating and directing inves It does, however, 



seem probable that the term hormone, like some ot' the use- 

 ful terminology of immunology, will be overworked, and 

 that investigators may deceive themselves as well as others 

 when they conclude : \ Driven relationship is au e\ 



ample of hoi- -illation. It has occurred to me that 



it may be useful in connection with this symposium upon 

 the internal secretions to review very brieily the state of 



our knowledge in regard to the hormones, with the purpose 



of discussing somewhat the probable nature of their action 

 and the extent of their distrihur. 



In treating this subject one must consider also the more 

 or less nearly related instances of combined activity of a 



