MAMMARY GLANDS- 117 ENDOCRIN RELATIONSHIPS 649 



impulses transmitted to the uterus upon stimulation of the mammae in 

 various fashions. 



In the line of clinical evidence, supporting the idea of a mammary 

 influence upon the uterus, may be cited the cases of Paterson, in which a 

 stimulation of the breasts resulted in relief from amenorrhea; then Soet- 

 erick, Mollath and others have reported uterine contractions in pregnant 

 women following electrical stimulation of the breasts, while Busch found 

 that stimulation of the mammae resulted in erection of the clitoris and 

 secretion from the ducts of Bartholin. Although the phenomena are 

 probably of simple reflex origin, it is within the range of possibility 

 that the mammary stimulation releases a hormone from the mammary 

 gland in a manner analogous to which stimulation of the splanchnics 

 causes a liberation of epinephrin from the suprarenals. Such an hy- 

 pothesis could be sustained or disproven by observing the effects of stim- 

 ulation of the mammae when all the nerves to either this tissue or the 

 uterus, or both, are cut. 



Further observations tending to demonstrate such an influence have 

 been made by Miiller and by Hermann and Stolper, who found that puer- 

 peral involution occurs sooner when the breasts are sucked than when not. 

 In addition, the fact that continued lactation leads to hyper involution, as 

 demonstrated by Trommel, Griiner, Vineburg (o-)(&), Engstrom, and 

 others, adds still more evidence of an underlying relationship between 

 uterus and mamma; whether or not this is neural, hormonal, or accom- 

 plished through some other intermediary is a. matter for further investi- 

 gation. 



The only directly available evidence that the mammary gland produces 

 an internal secretion is the work of MacKenzie, already discussed. His 

 results indicate that extracts of this tissue do contain substances stim- 

 ulatory to lactation, an indirect support for which conclusion is found in 

 the work of Wilms, Admitting such to be the case, we may consider 

 that we have here either a new type of endocrin gland, a type that is 

 self-stimulatory or autokinetic, or else that it is a property of certain types 

 of glandular tissues, such as the pineal, the thymus, the hypophysis, and 

 possibly others, to produce as a normal by-product of their metabolism, 

 or to contain in and of themselves as an innate constituent of their proto- 

 plasm, a substance which has a galactagogic activity, and that the produc- 

 tion of this stimulant is adventitious and not specific. 



Conclusion 



The one outstanding feature that is apparent in a consideration of 

 mammary activity and by activity is meant the growth, development, 

 and assumption of function of milk production is that the mamma more 



