i6o PATHOLOGY OF GESTATION. 



during gestation rendered still more impervious by the thick viscid mucus 

 secreted by its glands. Such being the case, it will be obvious that a 

 second impregation cannot occur, if it be necessary for this purpose that 

 the spermatozoa pass into the uterus, or even to the ovaries ; for the 

 whole is hermetically sealed after a certain time. For a second impregna- 

 tion to be accomplished during conception, fecundation must take place 

 before this closing-up of the uterus and Fallopian tubes — an interval too 

 brief after the primary impregnation to make much difference in the 

 respective developments of the young animals. In cases in which there 

 is a double uterus, or in which conception occurs in only one horn, super- 

 foetation is possible, and one parturition may not be followed by another 

 for some considerable time. 



SECTION II. — EXTRA-UTERINE PREGNANCY. 



In studying the development and progress of the ovule, after its escape 

 from the ovary and impregnation by the spermatozoa of the male, we saw 

 that a peculiar arrangement existed in the presence of the fringed border 

 at the extremity of the Fallopian tube, which grasped the ovule and per- 

 mitted it to be conveyed into the canal on its way to the uterus. From 

 certain causes which are not yet clearly understood, it sometimes chances 

 that the ovule, instead of taking this its normal course, either remains 

 in the ovary, is arrested in its progress through the tube, or, escap- 

 ing the fimbriated extremity of the latter, falls into the peritoneal 

 cavity, or glides between the folds of peritoneum constituting the broad 

 ligament, or between the serous and mucous membrane of the uterus ; in 

 all of which situations nature makes an effort to afford space and nutrition 

 for the embryo, and thus supply the place of the uterus. This effort, 

 however, as might be anticipated, is only partially successful, and after 

 attaining a more or less imperfect development, the fcetus perishes from 

 lack of nourishment. 



This abnormal deviation from ordinary gestation, happily very rare in 

 the domesticated animals, has received various names : such as Extra- 

 uterine pregnancy, Exfoetation, Conceptio vitioxa, etc. The first is that 

 usually employed ; and the different varieties are commonly designated 

 from the situation the ovum occupies. Thus we have (i) Ovarian foetation 

 when the ovum is detained in the ovary ; (2) Ovario-tubal, when lodged 

 partly in the F'allopian tube and partly in the ovary ; (3) Tubal, when 

 the tube is the situation j (4) Inte7-stitial, when the ovum enters the 

 parietes of the uterus at the termination of the tube, but is arrested 

 between the fibres before it can reach the cavity of that organ ; (5) Utero- 

 tubal, a compound of the two, the ovum being partly in the tube and 

 partly in the uterus ; (6) Utero-tubo-abdominal, when the foetus is in the 

 peritoneum, the umbilical cord passing through the tube to the uterus ; 

 (7) Tubo-abdominal, when the foetal envelopes are fixed in the tube, but 

 the foetus is developed in the peritoneal cavity ; and (8) Ventral or 

 abdominal fostation, when the embryo is formed and develops in the 

 abdomen. 



Extra-uterine pregnancy is not at all common in the domesticated 

 animals, and appears much more rare in them than in woman ; and 

 several of the varieties just enumerated have never, to my knowledge, 

 been observed in them. This may be fully accounted for by the different 

 disposition of their generative apparatus, the much less tendency of these 



