ON PARTURITION. 531
and the bulk such that the uterus is unable to retain it, added to which the quantity of excrementitious matter is so much in- creased that it cannot be contained by the membranes " l
Now it has been shown above that the uterine humours are not excrementitious. Nor do the weight and bulk of the foetus help us to a more probable explanation ; for the foetus suspended in water weighs but slightly on the placenta or uterus ; besides which some nine months' children are very small, much less in fact than many foetuses of eight months, nevertheless they do not abide longer in the womb. And as to weight, any twins of eight months are far heavier than a single nine months' child; yet they are not expelled before nine months are completed. Nor do we find a better reason in "want of nutriment ;" twins, and even more children, are abundantly supplied with support up to the full term ; and the milk which after delivery is sufficient for the nourishment of the child, could equally well, if transferred to the uterus, nourish the foetus there.
I should rather attribute the birth of the child to the follow- ing reason that the juices within the amnion, hitherto admi- rably adapted for nutriment, at that particular period either fail or become contaminated by excrementitious matter. I have touched on this subject before. The variation in the term of utero-gestation, occurring as it does chiefly in the human species, I believe to depend on the habits of life, feebleness of body, and on the various affections of the mind. And thus in the case of domesticated animals, owing to their indolence and overfeeding, the seasons both of copulation and production are less fixed and certain than in the wilder tribes. So women in robust health usually experience easy and rapid labours; the contrary holding good in those whose constitutions are shat- tered by disease. For the same thing befalls them that happens to plants, the seeds and fruits of which come later and less frequently to perfection in cold climates than in those where the soil is good and the sun powerful. Thus oranges in this country usually remain on the tree two years before they arrive at maturity ; and figs, w r hich in Italy ripen two or three times annually, scarcely come to perfection in our climate : the
1 p. 142.
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