On the other hand, however, it may be con sidered by some that the same data rather tend in a slight degree, as far as they go, to support the popular prejudice of the infecundity in a number of cases of the female twin, and her analogy in this respect with the free-martin cow ; for out of the forty-two instances which we have mentioned, we find six in which the woman has had no children, though living in wedlock for a number of years, or one out of seven of the marriages of such women has proved an unproductive one,—a proportion, we believe, considerably above the average of unproductive marriages in society in general, or among women of any other class. But perhaps, before drawing any very decided conclusion with regard to this point, a more extended foundation of data would be requisite than any we have hitherto been able to adduce, as it is perfectly possible that our having met with six exceptional cases may be a mere matter of coincidence.
As to the cause of the malformation and consequent infecundity of the organs of gene ration in the free-martin cow, we will not ven ture to offer any conjecture in explanation of it. It appears to us to be one of the strangest facts in the whole range of teratological science, that the twin existence in utero of a male along with a female should entail upon the latter so great a degree of malformation in its sexual organs, and in its sexual organs only. The
circumstance becomes only the more inexpli cable when we consider this physiological law to be confined principally or entirely to the cow, and certainly not to hold with regard to sheep, or perhaps any other uniparous animal.
The curiosity of the fact also becomes heightened and increased when we recollect that when the cow or any other uniparous ani mal has twins both of the same sex, as two males or two females, these animals are always both perfectly formed in their sexual organiza tion, and both capable of propagating. In the course of making the preceding inquiries after females born co-twins with males in the human subject, we have had a very great number of cases of purely female and purely male twins mentioned to us, who had grown up and be come married, and in only two or three in stances at most have we heard of an unpro ductive marriage among such persons.
Further, we may, in conclusion, remark that among the long list of individual cases of her maphroditism in the human subject that we have had occasion to cite, we find only one instance, (Eschricht's case of transverse herma phroditism,) in which the malformed being is stated to have been a twin. Katsky, however, Naegele, and Saviard have each, as before stated, mentioned a in which both twins were hermaphroditically formed in their sexual organs.