374 GENERATION. 



undergoes in menstruation have already been studied. 1 It 

 has been seen that, during an ordinary menstrual period, the 

 membrane has been increased three or four times in thickness 

 and has become more or less rugous. Without being able to 

 state from positive observation the character of the first changes 

 in the uterine mucous membrane preceding the descent of the 

 fecundated ovum for the opportunities for direct inspection 

 of these parts after fecundation and before the arrival of the 

 ovum are not frequent it is almost certain that this hyper- 

 trophy occurs and progresses. One of the most favorable 

 occasions for observing these early changes in the human 

 subject lately presented itself, and the appearances were 

 minutely described by Reichert. In this ca,se, the ovum was 

 lenticular, measuring nearly one-fourth of an inch in its long, 

 and about one-sixth of an inch in its short diameter. It was 

 covered with simple, empty, cylindrical villi, and was esti- 

 mated to be at from the twelfth to the thirteenth day of its 

 development, dating from fecundation. It was enclosed in 

 the decidua reflexa, and it was thought that this had been ac- 

 complished from twenty-four to forty-eight hours before the 

 death of the mother. 



According to Reichert, the thickening of the mucous mem- 

 brane of the uterus, which occurs at each menstrual period, 

 in case the ovum be not fecundated, is relieved by a flow of 

 blood and disappears ; but, if fecundation . take place, the 

 membrane continues to hypertrophy and to prepare itself to 

 enclose the ovum. In this process, when an ovum has been 

 fecundated, there are formed, upon the surface of the mucous 

 membrane, little elevations, or islands, provided with primary 

 and secondary papillae, everywhere except at their borders, 

 where the membrane is smooth and presents the enlarged 

 orifices of the uterine follicles. The ovum observed by 

 Reichert was found embedded in the parenchyma of one of 

 these islands ; and, as it was detached, several villi were drawn 

 immediately out from the uterine tubules. 

 1 See page 306. 



