DURATION OF PREGNANCY. 247 



antagonists prove nothing in the present case, and that women scarcely 

 ever know the precise period at which they were fecundated; but he 

 was wrong to appeal to the immutability of the laws of nature, and 

 the necessity of not interfering with social order. " If," cried he 

 in his enthusiasm, " you add to the means women already possess 

 of deceiving those about them, the faculty of giving posthumous chil- 

 dren to their husbands whenever they choose, what will become of the 

 order of succession, and even of the entire social order?" As if, in 

 the natural sciences, we ought not to seek after truth rather than 

 concern ourselves about social conventions! On the other hand, 

 Petit and Lebas too complaisantly admitted as proved what was not 

 even in every instance probable; so that in spite of the numerous 

 analogies with which they fortified their opinions, the question re- 

 mained undecided both by naturalists and physicians. 



636. At present the state of the case is changed; the antagonists 

 of Petit relied chiefly on the circumstance that, according to Aris- 

 totle, " the period of gestation in animals is limited to a fixed space, 

 and the term at which they bring forth is not subject to any varia- 

 tion." But as Buflfon had before pointed out, this assertion is wholly 

 false; Millot speaks of a cow which brought forth its calf five 

 days after the term, and of a cat that kittened nine days before the 

 regular period. Besides, M. Tessier, member of the Academy of 

 Sciences, a man whose honor and good faith cannot be called in 

 question, has removed all doubt upon this subject. 



He found that, of one hundred and sixty cows, which commonly 

 carry their young nine months, as women do, only three brought 

 forth on the two hundred and seventieth day; that fifty of them 

 went from the two hundred and seventieth to the two hundred and 

 eightieth, sixty-eight from the two hundred and eightieth to the 

 two hundred and ninetieth; twenty to the three hundredth, and 

 that five of them did not calve until the three hundred and eighth 

 day, which is thirty-eight days beyond the term. On the other 

 hand, fourteen of them calved from the two hundred and forty-first 

 to the two hundred and sixty-sixth; so that we find sixty-seven 

 days betwixt the two extremes. 



Of one hundred and two mares, whose term is eleven months, 

 three of them foaled on the three hundred and eleventh day; five 

 from the three hundred and tenth to the three hundred and thirtieth; 

 forty-seven from the three hundred and fortieth to the three hundred 

 and fiftieth; twenty-five from the three hundred and fiftieth to the 

 three hundred and sixtieth; twenty-one from the three hundred and 

 sixtieth to the three hundred and seventieth; and one on the three 



