vii THE STAGES OF LIFE AND DEATH 273 



Eighth week Embryo 30 mm. Lips, but palate and anus are wanting ; 

 fingers more distinct ; arm and forearm, thigh and leg are well defined ; 

 intestine withdrawn into the abdomen ; genital groove, near it the umbilical 

 cord ; development of placenta. 



Third month. Embryo 4-5 cm. ; 20-125 grins. ; Pupillary membrane ; 

 palate, anus ; intestine completely withdrawn into abdomen ; genital groove 

 much grown ; umbilical cord not so near to it ; placenta formed. 



Fourth month. Foetus 16-20 cm. ; 250 grins. An epidermic veil closes 

 the eyelids ; the sex begins to be distinguishable from the external genital 

 organs. 



Fifth month. Foetus 20-27 cm. ; 250-350 grms. ; epidermis, nails, hair, 

 down, genital organs well marked. Scrotum empty. 



Sixth month. Foetus 28-32 cm. ; 500 grms. Head a fourth of the body ; 

 face wrinkled. 



Seventh month. Foetus 32-36 cm. ; 1 kilo. ; the pupillary membrane 

 often begins to atrophy ; skin red ; vernix caseosa. 



Eighth month. Foetus 40-45 cm. ; 2-2-5 kilo. 



Ninth month. Foetus 45-50 cm. ; 2-5-3 kilo. 



Tenth month. Foetus 50-60 cm. ; 3-0-35 kilo. 



II. At birth foetal life ends and that of the new-lorn child 

 begins. Following Depaul we usually apply this term to the 

 child during its first twenty days of extra-uterine life ; it is a 

 short period, but a characteristic one from the physiological point 

 of view. During this period, indeed, phenomena of the utmost 

 importance take place : the substitution of the cardio-pulmonary 

 or third circulation for the cardio-placental or second circulation ; 

 the formation of the umbilicus ; the definite establishment of the 

 portal circulation ; and the involution of the foetal blood-vessels 

 which have become useless. 



The foetal apnoea continues for a short time after the 

 expulsion of the child, but is frequently forthwith interrupted 

 by an incomplete act of respiration due to reflex action set up by 

 the bulbar centre through the stimulating action of the cold air 

 on the cutaneous nerves of the new-born child. This initial 

 apnoea of the new-born child is caused by the fact that the 

 expulsive contractions of parturition do not usually cause total 

 detachment of the placenta from the uterine wall, hence after 

 expulsion the cardio-placental circulation continues, at all events 

 partially, and the blood of the new-born child has not as yet 

 acquired that degree of venosity which is necessary to act as a 

 stimulus capable of determining the rhythmic excitement of the 

 bulbar centre. The apnoea lasts 20-25 seconds, in rare cases as 

 much as 150 seconds (Bossi). It lasts longer in the child which 

 has been easily expelled, its blood being less poor in oxygen, than 

 in one born after a difficult labour ; it is longer in premature than 

 in mature cases, in which the consumption of oxygen is greater; 

 and is also longer when the expulsion of the after-birth is slow 

 than when it is rapid, because placental respiration ceases sooner. 

 The theory put forward in Vol. I. Chapter XIII. in explanation 

 of foetal apnoea will also hold good for the apnoea of the new-born 

 VOL. v T 



