412 ISIDOR GREENWALD 



present evidence, so far as the requirement of maintenance is concerned." 



The 'compilation of the observations on calcium showed that in 97 ex- 

 periments belonging to 14 investigations (10 of them by Sherman and his 

 collaborators), the indicated daily requirement varied from 0.27 to 0.82, 

 average 0.45, gram per 70 kilos. Sherman pointed out that, whereas only 

 one out of 224 supposedly typical American dietaries fell below the indicat- 

 ed protein requirement, one in six was deficient in calcium. If all that fell 

 below 3000 calories were increased to this level, none would be deficient 

 in protein, but one in seven would still be deficient in calcium. It is inter- 

 esting to observe, in this connection, that only one of Blatherwick's 32 

 army dietaries fell below 0.45 gram of calcium. 



The possible occurrence of a calcium deficiency and consequent advis- 

 ability of "liming the nation" seems recently to have attracted considerable 

 attention in Germany. Rubner (1920) has considered the question and has 

 concluded that with such foods as are used in Germany and are now avail- 

 able, there is no danger of a calcium deficiency for adults, so long as they 

 get enough food to satisfy their energy requirements. 



Rubner also calculated the values for the inorganic content of some 

 Japanese diets to European body weights with the results shown in Table 

 VI. The calcium content is much below Sherman's indicated requirement 

 and is certainly considerably below that which was customarily consumed in 

 Germany (page 415) but, if the analytical figures chosen by Rubner are 

 correct, is certainly adequate ivitli Japanese dietaries. It may not be with 

 European food materials. 



It is suggested by Rubner that the low fat content of Japanese diets may 

 be related to their low calcium content. If they ate more fat (vegetable 

 oils, etc.), the Japanese would not eat so much of their customary foods 

 and would thus obtain even less calcium than they do now and might then 

 suffer from a deficiency. 



A certain absolute minimum of calcium and of other inorganic ele- 

 ments is unquestionably needed, but there are observations that indicate 

 that this minimum may vary considerably under the influence of different 

 factors. The first and most obvious of these is the texture of the food and 

 the ease of digestion of the protein and carbohydrate contained therein. 

 Hart, Steenbock and Hoppert found that cows and goats lost much less 

 calcium on rations otherwise identical if they received fresh grass rather 

 than hay. McCluggage and Mendel found that the calcium and magnesium 

 of carrots and of spinach were poorly utilized by the dog. While it is 

 true that Rose found that the calcium of carrots was as well utilized by 

 women as that of milk, it, nevertheless, seems possible that in some other 

 foods, less readily digested, some inorganic constituents are not made 

 fully available for absorption. 



The nature of the chemical combination in which the element appears 



