ANOMALIES IN GESTA TION i^g 



the efforts of nature ; should the season be favorable it is allowed to re- 

 main at pasture, and frequently after some suffering the creature regains 

 its condition, even becomes fat, and may then be advantageously sold to 

 the butcher. Towards the spring-time, such an animal might conceive 

 again without having been delivered of the first foetus. 



In multiparous animals there can scarcely be a doubt that superfoeta- 

 tion may take place, and perhaps of all those which have been domes- 

 ticated the Rabbit furnishes the most striking example. With this 

 creature a new fecundation may occur in the middle of pregnancy. This, 

 of course, can be accounted for by the anatomical disposition of the 

 generative organs, the two cornua of the uterus opening into the vagina 

 independently ; so that a primary fecundation may occur only from one 

 ovary in the corresponding horn, the other remaining open and unoccu- 

 pied. 



In the Bitch, many observers have assured themselves that superfoeta- 

 tion is by no means unfrequent. Rainard, Blaine, and others speak of it. 

 Blaine says, " I am disposed to think that Bitches are capable of super- 

 foetation ; that is, they conceive more than once. If this is the case, a 

 Bitch may copulate to-day, and become impregnated, that in a day or two 

 she may copulate again, and again become impregnated. This is not 

 frequent, I believe ; but it certainly does happen, or we could not account 

 for the different periods at which the progeny sometimes appear. I have 

 known a week, and in one case even ten days, intervene between the 

 puppings ; but one or two days is not at all uncommon. As a still more 

 convincing proof, the whelps often appear of different kinds." 



It must be remembered that the Bitch remains in " heat " for three or 

 four days, and will seek for repeated intercourse with the male during 

 that period. It must, therefore, either be concluded that the last inter- 

 course was the successful one, or that one or more ova were impregnated 

 at each copulation. 



So far as our knowledge at present extends, we can neither positively 

 negative, nor absolutely admit, the possibility of superfoetation in the 

 larger domesticated animals. The cases recorded have not been sufficiently 

 investigated to convince those who deny the likelihood of two conceptions 

 taking place after a certain interval ; and it must be admitted that a true 

 explanation of such a singular occurrence has not yet been offered. A 

 lapse of time occurring between the birth of two animals is no strong 

 proof of a second impregnation during conception ; for, as we shall see 

 hereafter, when twins are conceived from the same intercourse, it may 

 and does happen that one ovum does not attain maturity so soon as the 

 other, and is either rejected or retained after a more or less lengthened 

 interval — a circumstance which might mislead. And again, with regard 

 to the size of twins, it is not at all unusual to find one larger and more 

 developed than the other, though both were produced at the same period. 

 Putting aside the question of superfoetation in animals, the anatomical 

 disposition of whose generative organs evidently permits such an occur- 

 rence, a little consideration will show that usually there are physical 

 obstacles which offer an insurmountable barrier to a second impregnation, 

 after conception has been achieved for a short time. Soon after that 

 event has taken place, the entrance to the uterus is closed by the shut sac 

 enveloping the embr\'o, and which adheres closely to the inner surface of 

 the organ throughout its entire extent — covering the orifices of the os 

 uteri and Fallopian tubes. In addition to this, the canal of the cervix is 



