DEVELOPMENT OF THE EMBRYO. 621 



her of facts on record, to prove that habitual mental conditions on the part of 

 the Mother may have influence enough, at an early period of gestation, to 

 produce evident bodily deformity, or peculiar tendencies of the mind. But 

 whatever be the nature and degree of the influence thus transmitted, it must 

 be such as can act by modifying the character of the nutritive materials sup- 

 plied by the Mother to the Foetus ; since there is no other channel by which 

 any influence can be propagated. The absurdity of the vulgar notion just 

 alluded to, is sufficiently evident from this fact alone ; as it is impossible to 

 suppose that a sudden fright, speedily forgotten, can exert such a continued 

 influence on the nutrition of the Embryo as to occasion any personal peculi- 

 arity.* The view here stated is one which ought to have great weight, in 

 making manifest the importance of careful management of the health of the 

 Mother, both corporeal and mental, during the important period of pregnancy ; 

 since the constitution of the offspring so much depends upon the impressions 

 then made upon its most impressible structure. 



769. It is frequently of great importance, both to the Practitioner and to the 

 Medical Jurist, to be able to determine the age of a Foetus, from the physical 

 characters which it presents ; and the following table has been framed by De- 

 vergiet in order to facilitate such determination. It is to be remarked, how- 

 ever, that the absolute Length and Weight of the Embryo are much less safe 

 criteria than its degree of Development, as indicated by the relative evolu- 

 tion of the several parts, which make their appearance successively. Thus it 

 is very possible for one child, born at the full time, to weigh less than another, 

 born at 8 or even at 7 months: its length, too, may be no greater; but the posi- 

 tion of the middle point of the body will usually afford sufficient ground for the 

 determination ; since, during the two latter months of pregnancy, the increas- 

 ing development of the lower extremities throws it lower down. 



Embryo 3 to 4 weeks. It has the form of a serpent; its length from three to five lines ; 

 its head indicated by a swelling; its caudal extremity, (in which is seen a white line, 

 indicating the continuation of the medulla spinalis,) slender, and terminating in the um- 

 bilical cord ; the mouth indicated by a cleft ; the eyes by two black points ; the members 

 begin to appear as nipple-like protuberances; the liver occupies the whole abdomen; 

 the bladder is very large. The chorion is villous, but its villosities are still diffused over 

 the whole surface. 



Embryo of 6 weeks. Its length from 7 to 10 lines; its weight from 40 to 75 grains; 

 face distinct from cranium ; aperture of nose, mouth, eyes, and ears perceptible; head 

 distinct from thorax; hands and forearms in the middle of the length, fingers distinct; 

 legs and feet situated near the anus; clavicle and maxillary bone present a point of 

 ossification; distinct umbilicus for attachment of cord, which at that time consists' of 

 the omphalo-meseraic vessels, of a portion of the urachus, of a part of the intestinal tube, 

 and of filaments which represent the umbilical vessels. The placenta begins to be formed ; 

 the chorion still separated from the amnion; the umbilical vesicle very large. 



Embryo of 2 months. Length from 16 to 19 lines; weight from 150 to 300 grains ; the 

 elbows and arms detached from the trunk; heels and knees also isolated; rudiments of 

 the nose and of the lips; palpebral circle beginning to show itself; clitoris or penis 

 apparent; anus marked by a dark spot; rudiments of lungs, spleen, and supra-renal 

 capsules ; ccecum placed behind the umbilicus; digestive canal withdrawn into the 

 abdomen ; urachus visible : osseous points in the frontal bone and in the ribs. Cho- 

 rion commencing to touch the amnion at the point opposite the insertion of the placenta; 

 placenta begins to assume its regular form; umbilical vessels commence twisting. 



* For some valuable observations on this subject, see Montgomery on the signs of 

 Pregnancy. Numerous cases have been recorded, during the last few years (especially 

 in the Lancet and Provincial Medical Journal), in which malformations in the Infant 

 appeared distinctly traceable to strong impressions made on the mind of the Mother, 

 some months previously to parturition; these impressions having been persistent during 

 the remaining period of pregnancy, and giving rise to a full expectation on the part of 

 the Mother, that the child would be affected in the particular manner which actually 

 occurred. 



f Medecine Legale, vol. i., p. 495. 



