GENERATION. 



469 



the first of these topics which we shall con- 

 sider, VIZ. 



1. Siiiifrfirttit'um. In the first section of 

 Part IV. it has been mentioned that in the 

 human female, as soon as the ovum has arrived 

 in the uterus, and even a short while before 

 that period, the passage through the mouth 

 and neck of the uterus is closed by a viscid 

 mucus, which opposes a firm barrier against the 

 entrance of seminal fluid, and thus prevents 

 the occurrence of subsequent or reiterated con- 

 ception. In some of the lower animals, on 

 the other hand, it would appear that several 

 consecutive conceptions not (infrequently occur, 

 and in some animals this may be considered as 

 the natural mode of generation. 



It becomes a point of some interest both in 

 a physiological and in a medico-legal view to 

 determine, whether, as has been supposed by 

 some, the same ever takes place in the human 

 species. 



The quadrupeds in which superfcetation 

 (as a second conception during pregnancy is 

 called) is said to occur possess a uterus with 

 two horns, and it may be that in them thp 

 product of the first conception lias occupied 

 only one of the cornua of the uterus, and that 

 the second conception occurred upon the other 

 or empty side. This may be the case in the 

 hare, for example, which is said to be particu- 

 larly liable to superfoHation. In woman also, 

 it has been supposed that a double form of 

 uterus, which is present in rare instances as a 

 malformation of that organ, may admit of a 

 second conception on one side in the course 

 of uterogestation confined to the other. But 

 though this may be regarded as possible, we 

 are not aware that any example of the actual 

 occurrence of pregnancy in both cornua of 

 a double uterus affords a satisfactory proof 

 of it. 



Great caution is necessary in admitting the 

 evidence of superfoetation, as many circum- 

 stances concur to render it very fallacious. 

 Women occasionally bear twins, or two chil- 

 dren differing greatly in size and apparent age; 

 and many are apt at once to form the conclu- 

 sion from thence that the two children must 

 have commenced their existence or have been 

 generated at different times ; but it is much 

 more likely in most of these instances, that 

 the different appearance in the size and con- 

 foimation of the children has arisen solely 

 from a difference in the rapidity and vigour 

 of their growth. In by far the greater num- 

 ber of such instances, the smaller of the 

 children bears obvious marks of being stunted 

 in its growth, and it is often deformed, blighted, 

 or dead and shrunk ; and even although this 

 were not the case and the children were both 

 alive, a mere difference of size of children 

 born at the same time must be regarded as 

 very slight evidence indeed of so great a devi- 

 ation from the usual phenomena of pregnancy 

 as superfatation. 



Those who believe in the possibility of the 

 occurrence of superfcetation found their belief 

 chiefly upon some rare instances of the birth 

 of more than one perfectly developed child at 



successive periods so remote from one another 

 that both cannot have been conceived at the 

 same time, and it must be admitted that these 

 cases, if correct, go far to prove the possibility 

 of superfuetation. 



In reviewing the cases of alleged super. 

 Conation two questions at once present them- 

 selves for consideration, viz. 1st, whether a 

 second conception may take place within a few 

 hours or days after the first, or we may say at 

 any period before the ovum is settled in the 

 uterus; and, second, whether this may occur 

 at a later period, as at two, three, four, or more 

 months after the first conception. 



The puppies of a bitch, we have already 

 mentioned, generally bear a resemblance to 

 more than one of the dogs with which she has 

 had connexion during the jreriod of heat, and 

 this period may extend to eight or nine days. 

 A mare, which had been covered by a stallion, 

 was five days afterwards covered by an ass, 

 and bore at the usual time twins, one of which 

 was a common foal, the other a mule.* 



Women have been known to bear two chil- 

 dren of different colour; and in one of these 

 instances the mother is said to have confessed 

 to having admitted the embraces of a black 

 servant a few hours after her husband, who was 

 white. 



Facts like these seem to shew that sexual 

 intercourse limited to an interval of a few days 

 (most probably before the uterus has been 

 closed by the decidua) may produce super- 

 fcetation. But we would remark that, although 

 it may be that the mechanical obstruction of 

 the decidua opposes an obstacle to the passage 

 of semen upwards, or the descent of a new 

 ovum into the uterus, there is obviously ano- 

 ther cause why superfcetation should not occur : 

 we mean that fundamental change in the con- 

 stitution which is induced by pregnancy, 

 similar to that which continues in the majority 

 of women during lactation. But for such a 

 constitutional change, we conceive continual 

 derangement of the function of utero-gestation 

 would attend that process in consequence of 

 the recurrence of some of the more general 

 symptoms of conception, even although a 

 lodgement of a new ovum in the cavity of the 

 uterus were impossible. 



The following cases serve to illustrate the 

 nature of the more important facts on record 

 which do not admit of an explanation, except- 

 ing on the supposition that superfcetation has 

 taken place. 



1. A woman bearing a full-grown male child 

 had neither lochia nor milk after its birth, and 

 a hundred and thirty-nine days afterwards 

 bore a second child a living girl, when the 

 milk and lochia came naturally. Eisenmann, 

 who had observed this case, explained the 

 occurrence by supposing that a double uterus 

 existed; but upon the woman's death some 

 time afterwards, no unusual structure was 

 found .f 



* Archiv. Gen. torn. xii. p. 125. Another 

 simil.ir instance is related in torn. xvii. p. 89, of the 

 game work. 



t Sec Burdach's Pbysiol. 



