344: GENERATION. 



fore, fix any limit to the vitality of these anatomical elements 

 under physiological conditions ; and we cannot say positively 

 that spermatozoids may not remain in the Fallopian tubes 

 and around the ovary, when intercourse has taken place im- 

 mediately after a menstrual period, until the ovulation follow- 

 ing. There is an idea, based upon rather general and indefi- 

 nite observation, that conception is most liable to follow an 

 intercourse which occurs soon after a monthly period ; but it 

 is certain that it may occur at any time. It is extremely 

 probable that, during the unusual sexual excitement which 

 the female generally experiences after a period, the action of 

 the internal organs attending and following coitus presents 

 the most favorable conditions for the penetration of the fe- 

 cundating elements, and this may explain the more frequent 

 occurrence of conception as a consequence of intercourse at 

 this time. 



Mechanism of Fecundation. In considering the intimate 

 mechanism of fecundation, we may begin with the proposi 

 tion that this is accomplished by an actual union of the sub- 

 stance of the ovum with a greater or less number of sperma- 

 tozoids. This fact, which has long since been positively de- 

 monstrated by experiments, affords a material explanation of 

 hereditary transmission, not only of maternal, but of paternal 

 physical and mental qualities. 



There are many questions connected with hereditary trans- 

 mission, which, if they were susceptible of any thing ap- 

 proaching a positive scientific explanation, would be of great 

 interest and might appropriately be discussed in a work 

 on physiology ; but, although the facts of hereditary influ- 

 ence, as regards the inheritance both of physiological and 

 morbid attributes and tendencies, the influence of the mater- 

 nal mind on the development of the foetus, the effects of pre- 

 vious pregnancies, etc., cannot be doubted, their consideration 

 would involve little more than a mere enumeration of re- 

 markable phenomena. 



