ACTION OF THE FEMALE. 



601 



by imbibition (Fig. 13). Mr. Wharton Jones, on the other hand, (who was 

 the first to observe this stage of the process, and to maintain that the Chorion 

 is formed in the Fallopian tube,) asserts that the gelatinous matter is first 

 deposited around the Zona Pellucida ; and that the Chorion is subsequently 

 formed from or upon it. It appears to the Author, that the gelatinous envelop 

 is strictly analogous to the white of the Bird's egg ; and that the Chorion 

 corresponds with its enveloping membrane, and is probably formed in the same 

 manner. The gelatinous-looking envelop is probably of an albuminous 

 nature in reality ; and the texture of the Chorion, which is seen to be fibrous, 

 as soon as it can be clearly distinguished, is probably derived from the Fibrin 

 poured out from the lining of the Fallopian tube. The appearance of cells 

 noticed by Dr. Barry, corresponds with what is witnessed in other fibrinous 

 effusions ( 560). From the surface of the Chorion, a large number of villous 

 prolongations afterward shoot forth ; these serve as absorbing radicles, and 

 form the channel through which- the Embryo is nourished by the fluids of the 

 Parent, until a more perfect communication is formed. 



748. We have now to speak of the changes in the Uterus, which take place 

 in consequence of Conception, and which prepare it to receive the Ovum. Of 

 these the most important is the formation of the Membrana Decidua, so called 

 from its being cast off at each parturition. This membrane has been usually 

 supposed to be a new formation ; and has been described as originating in 

 coagulable lymph thrown out on the inner surface of the Uterus, into which 

 vessels are prolonged from the subjacent surface. It appears, however, from 

 the late researches of Dr. Sharpey and Prof. Weber,* that this is not the true 

 account of it ; and that the Decidua is really composed of the inner portion of 

 the Mucous membrane itself, which undergoes a considerable change in its 

 character. The Mucous membrane of the Uterus had been observed by Dr. 

 J. Reid to possess, on its free surface, a tubular structure ; not very unlike 

 that which has been described as existing in the lining membrane of the 

 stomach ( 704 and Fig. 170). This tubular portion becomes thickened and 



Fig. 160. 



Fig. 181. 



Section of the Uterus, showing the position 

 of the decidua vera; a, cervix; &, 6, orifices 

 of Fallopian tubes; c, decidua vera; d, ca- 

 vity of uterus. 



Section of the Uterus, at entrance of ovum 

 /, surrounded by its chorion g; a, cervix; 

 6, 6, Fallopian tubes; c, decidua vera; d, ca- 

 vity of uterus ; e, decidua reflexa. 



51 



* Mailer's Physiology, pp. 1574-1580. 



