392 THE VITAMINES 



McKay (1583) frequently observed a defective enamel in certain 

 districts in the Rocky Mountains, where the diet was inadequate. 

 Castilla (1584) often observed caries and defective enamel after 

 colitis and other disturbances of the stomach and intestinal tract 

 in children from 1| to 4 years old. Considerable progress has been 

 made in this field since the problem has been undertaken experi- 

 mentally. 



Miller and Gies (1585) studied the question of teeth formation in 

 rats from the standpoint of the calcium and magnesium metabolism. 

 M. Mellanby (1586) studied the condition of the teeth in young 

 rachitic dogs. On diets that were poor in vitamine A, the following 

 changes were visible : 



1. Delayed falling out of the milk-teeth. 



2. Delayed appearance of permanent teeth. 



3. Disarrangement in the position of the teeth 



4. Lack of or defects in the enamel. 



5. Diminished calcium content. 



In quickly growing teeth, the defects were even more pronounced. 

 Vitamine A, in the form of cod liver oil or butter., exerted a very 

 favorable influence. Zilva and Wells (1587) observed, in guinea 

 pigs and monkeys on a scurvy-producing diet, a fibroid degeneration 

 of the tooth pulp. These changes occur very early, often before all 

 other scorbutic symptoms. The findings on scorbutic guinea pigs 

 were confirmed by Percy R. Howe (1588), Robb, Medes, McClendon, 

 Graham and Murphy (1588a) and developed further experimentally 

 by P. R. Howe (1588b). The latter managed, by means of a partial 

 lack of vitamine C, to keep the animals (guinea pigs and rabbits) 

 alive for about one year, so that the results were more definite. 

 The teeth were carious, poor in calcium and bent, with 

 Pyorrhoea alveolaris. There was also observed a disease of the 

 joints, resembling rheumatism or Arthritis deformans. Ballantyne 

 (1589) found that 98 per cent of pregnant women show carious teeth. 

 This may well be explained by the greater requirements for vita- 

 mines, calcium salts, etc. Sinclair (1590) rightly emphasized that 

 precautions for the good condition of the teeth of the child must 

 begin with the pregnant mother, who should receive the best possible 

 nourishment. The effect of the diet on the teeth does not appear 

 to be related to any one specific vitamine, but vitamine A, because 



