On the alleged infecundity of females born co-twins with males : with some notes on the average proportion of marriages without issue in general society / by James Y. Simpson.
- James Young Simpson
- Date:
- [©1844?]
Licence: Public Domain Mark
Credit: On the alleged infecundity of females born co-twins with males : with some notes on the average proportion of marriages without issue in general society / by James Y. Simpson. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
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![But in 15 of the 94 cases, tlie motlier had as yet only one child at the time her case was noted, having either only lived in wedlock for a year or two previously, or the single child being the result of illegitimate intercourse. If we deduct these 15 cases only (though other mothers with a young and increasing family of two or three children might be excepted from the calculation in the same way,] and on the same grounds,) we will have then 79 mothers producing 364 children ; or, again, to state it in reference to the supposed standard of 100 rfiarriages, we have this result as the degree of fruitfulness of such co-twin females. In every Marriages. No. of children. Prop, of children to each marriage. 100 4«;0 4r% The whole inquiry detailed in the few preceding pages forms an apt illustration of an old remark, that in medicine it often re- quires a much greater extent of observation and research to dis- prove satisfactorily an alleged and accredited fact than was ever expended, either upon the original development or subsequent confirmation of it. In the present instance, the results have turned out to be perfectly contradictory of the opinion which I, in common with others, held regarding the infecundity of the female in double sexed twins, when I commenced looking into the subject; and instead of finding my preconceived ideas confirmed by the investigation, they have, on the other hand, been completely con- futed by it. For the data that I have adduced do, so far as they go, evidently prove : 1. That, in the human subject, females born co-twins with males are, when married, as likely to have children as any other females belonging to the general community. 2. That, when they are married and become mothers, they are, in respect to the number of their children, as productive as other females. 3- That the same law of the fecundity of the female in opposite sexed twins seems to hold good among all our uniparous domestic animals, with the exception of the cow alone. Indeed, the strong confirmatory evidence which theprecedino- in- quiry affords of this last exceptional point constitutes one of its most interesting results. For certainly it cannot but be considered as an extraordinary circumstance, that, in the cow, the twin exist- ence in utero of a male along with a female should, as a general principle, lead, 1. To so great a degree of malformation as we have described in the sexual organs and in the sexual organs only. 2. That this malformation should be limited entirely to the reproduc- tive organs of the female twin, while those of the male twin are per- fectlyandfuUydeveloped. 3. Thattliissexual malformation should, apparently as far as we yet know, occur in the case of twins in the cow only, and in this species of uniparous animal alone. The curiosity of the fact becomes heightened and increased when we](https://iiif.wellcomecollection.org/image/b21470510_0016.jp2/full/800%2C/0/default.jpg)
