66 GENERAL EMBRYOLOGY. 
total length of the foetus, from vertex to heels, is from 30-32 em. (12-12? in.), and its 
average weight is about one kilogramme (25 Ibs.). 
The seventh month.—The skin is still a dirty red colour but it is lighter than 
in the previous month. ‘The body is more plump on account of a greater deposit of sub- 
cutaneous fat. The eyelids reopen, and the foetus is capable of living if born at this 
period. Its total length at the end of the month, measured from vertex to heels, is 35-36 
em. (14-142 in.), and its weight is about one and a half kilogrammes (3% Ibs.) 
The eighth month.—The skin is completely covered with sebaceous deposit which 
is thickest on the head and in the axillz and groins, and its colour changes to a bright 
flesh tint. The umbilicus is further from the pubis, but it is not yet at the centre of the 
body. The total length of the foetus, from vertex to heels, is 40 em. (16 in.), and its weight 
varies from 2 to 24 kilogrammes (43-55 Ibs.) 
The ninth month—The hair begins to disappear from the body but it remains 
‘long and abundant on the head. The skin becomes paler, the plumpness increases, and 
the umbilicus reaches the centre of the body. At the end of the ninth month, when the 
foetus is born, it measures about 50 cm, from vertex to heels (20 in.), and it weighs from 
3-34 kilogrammes (6,%-73%5 lbs.) 
The age of a foetus may be estimated approximately by Hasse’s rule—viz.: Up to the 
fifth month the length in centimeters, the lower limbs being included, equals the square of 
the age in months, and after the fifth month the length in centimeters equals the age multiplied 
by five. 
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