S50 THE PHYSIOLOGY OF REPRODUCTION 



a loss of calcium. This occurred particularly at the end of the sixth 

 month (thirtieth week) when there was a sudden increase in the foetal 

 requirements of Ca. It is necessary to emphasise a point in 

 Hoffstrom's observations, the importance of which has not been 

 sufficiently reeognised, namely the nature of the diet on which 

 Hoffstrom's patient lived. She was allowed a free choice of food 

 and from a sample menu given in Hoffstrom's paper it is clear that 

 the diet was particularly rich in calcium. She consumed a litre of 

 milk a day in addition to other calcium-rich foods and the result is 

 an average weekly intake of Ca of 1'7 gm. throughout the whole of 

 pregnancy. Tigerstedt calculates that the amount of Ca necessary to 

 maintain a normal non-pregnant organism does not exceed 1 gm. Ca 

 per week. When the diet is poor in calcium, as in the experiments 

 of Dibbelt ^ on a pregnant bitch, the embryos do not suffer a loss of 

 calcium. The deficiency is made up entirely by the maternal tissues, 

 which in Dibbelt's experiments had to furnish 4-2 gm. Ca. The calcium 

 content of the blood is said tb be increased during pregnancy.^ These 

 considerations emphasise the importance of including in the dietary 

 of pregnant women food material rich in calcium such as milk, butter, 

 cheese, green vegetables, certain fruits such as oranges, lemons, etc. 

 With reference to this point it is important to note that margarine is 

 practically free from calcium, while butter is a food particularly rich 

 in calcium. 



(c.) Magnesium. — The magnesium intake and output was also 

 observed by Hoffstrom. The amounts which came into question are 

 much smaller and the results are irregular. On the whole there is a 

 magnesium retention amounting on an average to 0"013 gm. per day 

 with an average daily intake of 0'282 gm. which Hoffstrom considers 

 to be low. There arej)eriods of magnesium loss. But even with 

 this low intake Hoffstrom's case retained during the whole of 

 pregnancy a total of 2'44 gm., of which 0'98 gm. was fixed by the 

 foetus, so that the maternal organism gained. 



(d.) Phosphorus. — The phosphorus metabolism runs as a rule 

 parallel to the nitrogen metabolism. The same has been observed in 

 pregnancy (V. Eeke,^ Schrader*). Jagerroos,^ however, showed an 

 equilibrium between intake and output of phosphorus in a pregnant 

 dog which showed a distinct loss of nitrogen. But . since such 



' Dibbelt, " Die Bedeutung der Kalksalze f. d. Schwangerschaf t und Still- 

 periode, etc.," Ziegler's Beitr. path. Anat., vol. xlviii., 1910. 



2 Lamers, "Der Kalkgehalt des menschlichen Blutes, etc.," Zeitsch.]. Qehwtsh. 

 u. Qynah., vol. Ixxi., 1912. 



^ Ver Eeke, loc. cit. 



* Schrader, " Stoffwecbael wahrend der Schwangerschaf t," Arch. f. Oynak., 

 vol. Ix., 1900. 



* Jagerroos, loc. cit. 



