COXSEKVATIOA' OF SKELETAL CALCHM ATOMS THKOl (iH LIFE 



225 



Table 3. — Loss ok ^^Ca «y the Uniformly Labelled 

 Skeleton of Mice with Time Indicated by Measurements ok 

 THE Radioactivity of the Skeleton of Different Mkmbkks 

 OF a Litter Killed at Various Times. The Mice wkre Born 

 FROM Active Mothers and were Administered ^^Ca until the 

 First Member of the Litter was Killed 



No. of Utter 



II 



III 



IV 



V 



VI 



VII"" 



Age in days '^(ja content 



106 

 106 

 231 

 325 



56 

 129 

 266 



99 

 214 

 308 

 392 

 503 



100 

 66 

 63.8 



100 

 81.4 

 60.7 



100 

 77.7 

 55.5 

 55.9 

 50.1 



* Cheese and egg shells were added ad lib. to the standard "gard-bred" diet. 



grown mice are present after the lapse of more than a year and can tlius 

 be considered to be unreplaceable during life. 



Figs. 1 and 2 and Table 4 show the results of some of our experimenis 

 in which the litter, born from active mothers, was kept from birth on a 

 ^Ca-free diet. These experiments include the results obtained between 

 the third and the 560th day after birth, thus almost the lifetime of the 

 mouse. The percentage of ^^Ca lost between day 3 and day 560 works 

 out to be 53 per cent and 44 per cent, respectively. The mean loss of 



15 Hevesv 



