FCETUS. 



ehorion. It contains several blood res- 

 sels, which are best seen in recently dis- 

 charged secundines. It adheres closely 

 to the uterus on one side, and to the 

 ehorion on the other. The laceration of 

 the vessels, which this membrane re- 

 ceives from the^uterus, accounts for the 

 hemorrhage which follows its separation. 

 At the edge of the placenta it divides into 

 two layers, which pass over the two sur- 

 faces of that organ, and form its uterine 

 portion. 



The liquor amnii is the fluid immedi- 

 ately surrounding the bdy of the child, 

 and so called from the membrane enclos- 

 ing it. Its usual quantity is about two 

 pints. It is a clear, transparent fluid. 



The child, while in the uterus, is natu- 

 rally contracted into an oval form, adapt- 

 ed to the figure and circumstances of its 

 habitation. The vertex of the head makes 

 one end of >he oval, and the nates the 

 other. One side or edge of the oval is 

 formed by the occiput, the back part of 

 the neck, and the incurvated trunk ; the 

 other is made by the forehead and the 

 mass of contracted and conglomerated 

 limbs. The chin is close to the breast, 

 the trunk bended forwards, the knees 

 close to the fore parts of the hypochon- 

 dria, the legs drawn to the back parts of 

 the thighs, and the upper extremities 

 contracted into the vacant space betwixt 

 the forehead and knees. The more or less 

 compact form of the child depends on the 

 quantity of the liquor amnii; when that 

 is small, the uterus moulds the child into 

 various forms, and often produces defor- 

 mities of the limbs. The head is placed 

 downwards with respect to the mother, 

 and the nates upwards. 



The usual weight of the child at the 

 time of birth is from five to eight pounds ; 

 of several thousands weighed at the Bri- 

 tish Lying-in Hospital, the largest weigh- 

 ed lllb. 2oz. the smallest was above 4lb. 



The head, upper part of the trunk, and 

 upper extremities, are very large, when 

 compared with the lower parts of the 

 body. The surface of the skin is covered 

 pretty generally with a white sebaceous 

 matter. 



Peculiarities in the Structure of the Fcetus. 



These are on the whole numerous ; but 

 we shall briefly enumerate the most im- 

 portant oiily. 



The first which claim our attention are, 

 some points respectii,; the heart and 

 large-blood-vessels; which we may sup- 



VOL. V. 





pose absolutely necessary to the life oi 

 the child, while it draws nourishment 

 from the mother, and cannot enjoy respi- 

 ration. As the foetus in utero cannot 

 breathe, the circulation of its blood, 

 through the lungs would be useless : 

 hence that fluid can go from the right to 

 the left side of the heart by means of an 

 opening called the foramen ovale, and 

 placed between the two auricles, and of 

 a communicating canal from the pulmo- 

 nary artery to the aorta, called ductus ar- 

 teridsus. The umbilical arteries are con- 

 tinuations of the internal iliacs, taking the 

 blood from the child to the placenta ; 

 from which it is brought back by the um- 

 bilical vein, and circulated through the 

 liver. 



The lungs are small and compact ; and 

 as they have not yet received air, they 

 are specifically heavier than water. This 

 is an important point, and is usually re- 

 ferred to in trials for chi Id-murder, in or- 

 der to determine whether the child was 

 born alive or no. If the lungs sink in wa- 

 ter, it is considered a still-born case ; and 

 if they float, the probable inference is, 

 that the child has breathed, but it would 

 be a very rash conclusion that it had, 

 therefore, been murdered. Much cau- 

 tion and consideration of concomitant cir- 

 cumstances must be employed in making 

 use of this proof. Putrefaction will dis- 

 engage air that may make the lungsfloat. 



The thymus gland, in the chest, is very 

 large in the foetus ; it gradually shrinks 

 after birth, until it entirely disappears. 

 Its use is nnknown. 



The pupil of the eye is shut until the 

 seventh or eighth month, by a thin pelli- 

 cle called membranu pupillaris. As a ge- 

 neral observation, the eye and ear are 

 very perfect at the time of birth, and 

 almost as large as they ever will be. (N. B. 

 This does not apply to the external ear.) 



The small intestines have no valvulae 

 conniventes. The large are filled with a 

 durk green mucous and semifluid sub- 

 stance, called mcconium. The liver is of 

 an immense size, and fills two-thirds of 

 the belly. 



The renal capsules are very large, equal 

 indeed to the kidnies themselves. Their 

 use is unknown. 



The testicle is placed originally in the 

 abdomen, near the kidney ; but it passes 

 into the scrotum towards the latter 

 periods of gestation. Sometimes it does 

 not descend on one or both sides till af- 

 ter birth, and sometimes not even during 

 life. 



Aa 



