196 THE VITAMINS 



In a later paper Givens and McClugage (1920a) reported further 

 that a daily allowance of 10 grams of raw white potato was appar- 

 ently more than sufficient to protect the growing guinea pigs from 

 scurvy for the duration of the experiment, 129 days. Cooking the 

 potatoes in water at 100° C. for 15 minutes caused only a slight re- 

 duction in antiscorbutic value, while cooking for an hour at the same 

 temperature reduced the vitamin content to such an extent that the 

 disease could not be arrested by feeding 15 grams daily of the product. 

 Scurvy was checked in two animals by feeding 10 grams of potatoes 

 cooked in 0.5 per cent citric acid for 1 hour. 



With potatoes dried at 35° to 40° C, death from scurvy was 

 slightly delayed by an amount (2.5 grams) equivalent to 10 grams of 

 the fresh product, while with double the amount life was prolonged 

 still further. One out of four animals on a daily dose of 2.5 grams dried 

 at 55° to 60° C. and one out of four animals on a daily dose of 2.5 

 grams dried at 75° to 80° C, showed signs of scurvy at death. On 

 heating at 100° C. for 1 hour the products dried at these temperatures, 

 no protection was secured in any case. 



Scheunert (1929) found old sprouted potatoes to be somewhat 

 lower in their content of vitamin C than new potatoes, to which he 

 gave much higher values than usually reported. According to him 3 

 grams of new white potatoes fed raw and 4 grams cooked with or 

 without skins sufficed for the best development of guinea pigs. Steam- 

 ing or ordinary cooking in water appeared to be less destructive than 

 cooking in the pressure cooker for even a very short time, 12-14 

 minutes. 



Sweet potatoes are probably a fairly good source of vitamin C. 

 Delf (1921, 1922) in the report of her investigation of South African 

 foods recommended the introduction of sweet potatoes into the ration 

 of the Rand miners when fruits such as oranges, pineapples and tanger- 

 ines were not available. The minimum protective dose in her experi- 

 ments lay between 4 and 5 cubic centimeters of the juice or about 13 

 grams of the raw vegetable. 



The dasheen or taro, a staple root food of the Pacific Islands and 

 coming into more general use in certain sections of the country as 

 a substitute for the potato, is low in vitamin C according to Miller 

 (1927) who worked with the steamed vegetable and poi, the fermented 

 paste prepared from it according to methods followed in Hawaii. 



Stems such as asparagus and celery would seem to be worthy of 

 attention as regards antiscorbutic value but have not been studied to 

 any extent. Rhubarb was shown to possess antiscorbutic power by 



