200 THE FCETUS. 



color, and but slightly extensible; the nails are evident; the umbili- 

 cal cord far removed from the penis or clitoris. No pupil can be 

 distinguished, and the foetus is from six to seven inches long. 



512. At six months, the period of viabilite, the down and the 

 sebaceous deposit are visible, at least in the axillae and groins. The 

 hairs of the head may be easily distinguished from those that grow 

 upon other parts of the body; the eyelids are no longer transparent; 

 it has been said that there is at this period no pupil; but it has ap- 

 peared to me, on the contrary, to be extremely large; the xiphoid 

 cartilage occupies the middle of the great axis of the foetus, whose 

 whole length is from eight to nine inches. 



513. A.t seven months the hair is longer, and not so pale, the 

 down and cutaneous induitus more generally diffused; the skin is 

 less colored; the nails are large; the raembrana pupillaris bursts, 

 according to the authors; but it is by no means certain that this 

 membrane really exists in the manner usually understood: I have 

 reason to think that the iris originates at first as a simple ring, which 

 grows concentrically, so as at least to leave the opening commonly 

 called pupil or apple of the eye. The navel is still below the middle 

 of the foetus; the external genital organs are all apparent, except the 

 testicles in the male, and the foetus is about ten inches long. 



514. At eight months the foetus is only distinguished by its greater 

 maturity; its length is about eleven inches. Its hair is more or less 

 colored; its skin, covered with sebaceous matter and down, is thick, 

 and not so smooth as before; the lower jaw, which at first was very 

 short, is now almost as long as the upper one, and the nails exhibit 

 a certain degree of consistency. 



515. M term. The development and weight of a well formed 

 foetus, at term, are far from being alike in all cases. The knowledge 

 of them, however, even if approximative, is so important in the 

 practice of midwifery, that their extremes and average ought to be 

 sought for with great care. At this period, the length of the occipito- 

 coccygeal diameter is twelve inches, but the average length of a 

 foetus straightened out and taken from the heel to the vertex, is 

 eighteen inches, according to the very multiplied experiments of 

 professor Chaussier; seventeen, sixteen, nineteen, twenty, and even 

 twenty-two inches, are also pretty common measurements, but it is 

 rare to meet with only twelve inches, or to find twenty-three. The 

 instances of children twenty-six, twenty-eight, thirty, and even thirty- 

 six inches in length, or of only ten, eight, or even six inches, which 

 we find in old scientific collections, instances which the common 

 people always receive with cordiality, may be boldly classed among 

 other popular stories. 



