126 PLAIN FACTS FOR OLD AND YOUNG 



cate that in general, those enjoy the best health who 

 lose but small quantities of blood in this manner. 



Some recent observations respecting the nature of 

 menstruation, have unsettled the old theories respect- 

 ing this function, and given rise to much discussion. 

 The most plausible theory, and one which differs very 

 materially from the old, is that of Loewenthal. The 

 views promulgated by this author are of so much in- 

 terest that we take this opportunity of presenting them 

 at some length in the following translation published 

 in the Detroit Lancet: 



1. Menstruation recurs periodically. It is marked 

 by an individual periodicity. Any deviation from the 

 ordinary rhythm (due to strong psychical influences, 

 changes of the mode of life, etc.) will, in a short time 

 after removal of the cause, return to the special normal 

 periodicity. 



2. The kind and duration of the flow is different in 

 different women. 



3. Anatomical and physiological changes take place 

 in the mucous membrane of the uterus as follows: 



(a) There is a thickening of the mucous membrane, 

 which commences about ten days before the menstrua- 

 tion, and is analogous to decidual formation in the 

 early stages of pregnancy. 



(b) During the flow, disintegration of the outer 

 layer of the mucous membrane takes place, which is 

 completed in ten days. 



(c) The swelling of the mucous membrane at first 

 takes place especially in the outer layer, and affects the 

 lymph vessels, which are dilated, and not the blood- 

 vessels; the latter only enlarge at a later period, that 

 is, just before the flow commences. Congestion does 

 not cause the thickening of the mucous membrane. 



