vi PREFACE 



recently that Prof. Starling suggested the term "hormone'' 

 for the active principles of those internal secretions which act 

 as chemical messengers and have a definite specific stimulating 

 effect upon other and sometimes distantly situated organs. 

 The result of such a stimulus is usually either growth or, 

 in the case of a glandular organ, secretion, and one of the most 

 obvious effects of the reproductive hormones is to produce 

 growth. This, however, is far from being the only effect, since 

 the influence of the testicular and ovarian hormones is mani- 

 fested in greater or less degree throughout the whole body, and 

 is extended to the psychical activities, as is plainly manifested 

 in the display of sexual feeling and those associated phenomena 

 which play so important a part in the activities of the 

 organism. 



There is one important respect in which the endocrine 

 functions of the gonads appear to differ from those of other 

 organs of internal secretion, and that is in being cycHcal. For 

 although the ovarian and testicular hormones are probably 

 produced to some extent at all times, especially throughout the 

 period of reproductive Ufe, the secretions change in quantity, 

 and probably also in the female in composition, with certain 

 recurrent seasons. This periodicity is apparently partly 

 inherent in the reproductive organs themselves, but it is also 

 influenced by external or environmental factors such as 

 nutrition and seasonal and climatic conditions. Numerous 

 instances of the cycHcal activity displayed by the gonads and 

 the modes of working of their internal secretions, with many 

 cognate matters, are given by Prof. Lipschiitz in the pages of 

 the present work. 



The book was first published at Berne in 1919 under the title 

 Die Puhertatsdrilse und ihre Wirkungen. The name "puberty 

 gland" was given by Prof. Steinach, of Vienna, to denote the 

 testicular and ovarian endocrine organs, since these glands, 

 although they are beUeved to exert their influence on the 

 organism from early stages of development onwards, show an 

 especially accentuated activity at the phase of life when the 

 gonads become mature. In the present edition, which contains a 

 considerable amount of new matter, Prof. Lipschiitz has thought 

 it expedient to change the name to The Internal Secretions of the 

 Sex Glands, a title that indicates more accurately and more 

 completely the contents and character of the book. 



