INTRODUCTION. 189 



help rather than a hindrance to digestion of proteids, whereas 

 the inference from the natural digestion experiment is just the 

 reverse. 



It is admitted, of course, that it is almost impossible to con- 

 duct metabolism experiments with infants as subjects, and they 

 are the very class most concerned. Among the many experi- 

 ments carried on with very young animals are those of Annett 

 (l). The subject of his experiments were kittens three weeks 

 of age. The milk fed was treated with boric acid. The amounts 

 for the two experiments were respectively 40 and 80 grains of 

 boric acid per gallon of milk. At the end of the four weeks, all 

 kittens fed on the adulterated milk were dead, while the con- 

 trol lot, which were fed pure milk, were alive and healthy. 



This series of experiments was followed by a similar one, 

 the milk, however, being treated with formaldehyde in place of 

 boric acid. The results of the latter experiments were not so 

 conclusive as were those obtained from the boric acid test. At 

 the same time, the data obtained are of more than passing 

 interest. In the first experiment, the milk contained 7 i)arts 

 formaldehyde to 50,000 parts milk. In the second experiment, 

 the proportion of formaldehyde was just doubled, or 1 to 25,0()(), 

 In the third experiment, the proportion of formaldehyde was 

 again doubled, or 1 part to 12,500. It was noted that the gain 

 in weight in all three experiments bv the control kittens receiv- 

 ing only pure milk was far ahead of the gain of those receiving 

 the adulterated article. This is particularly emphasized in the 

 third experiment. These results are at variance with many of 

 the findings recorded for artificial digestion experiments but as 

 they have stood the test of criticism and investigation they 

 must be accorded serious consideration. 



It is perhaps gratifying to know that Annett's views on this 

 subject are ably supported b>- the reports of Wiley (6) on the 

 influence of food preservatives and artificial colors on digestion 

 and health. The subjects of Wiley's experiments were all 

 healthy young men, and it was clearly shown that the preserv- 

 atives studied, viz., borax, salicylic acid, sulphites and benzoic 

 acid, and formaldeh>'de, were deleterious substances and pro- 

 duced digestive disturbances- 



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