1920.] 



Potatoes Immune from Wart Disease. 



49 



THE COMPOSITION OF POTATOES 

 IMMUNE FROM WART DISEASE. 



E. J. Russell, D.Sc, F.R.S., 



Director of the Rothamsted Experimental Station. 

 Hitherto the farmer has not concerned himself much with 

 the feeding value of the foods grown on the farm for human 

 consumption, and a complaisant public has asked for nothing 

 more than a natural unadulterated product. Until 1917 

 no attempt was made in this country to investigate the 

 value of different varieties of potatoes as human food. Actual 

 feeding tests on human beings had, however ; been made in 

 America. Few chemical analyses of British potatoes had been 

 made, apart from the dry matter and the nitrogen determinations 

 of Lawes and Gilbert in 1S87. Detailed chemical analyses 

 of potatoes are by no means easy and would not necessarily 

 be very helpful. Physiologists regard the dry matter content 

 as an important criterion, and ordinary conventional analytical 

 methods indicate nothing better. Judged from this standpoint 

 the analytical results show that absolutely unimpeachable 

 potatoes may vary considerably in their food values, the extreme 

 limits in the ordinary varieties on the market ranging from 

 17-6 to 29-1 per cent, of dry matter. It is possible that some 

 day a different method of purchasing will prevail, and that the 

 dry matter of the crop may be taken into consideration in 

 assessing its market value. This would be both logical and 

 legitimate, and if ever such a method should come to be 

 adopted it is gratifying to know that the new immune varieties 

 will, so far as these analyses indicate, compare favourably 

 with the old. 



During 191 8 the Food Production Department arranged 

 for determinations to be made of the amount of dry matter 

 in different commercial varieties of potatoes grown in 1917 

 under different conditions in England. The results of the 

 investigations have been published in the Report on the Com- 

 position of Potatoes grown in the United Kingdom, issued 

 by the Food (War) Committee of the Royal Society.* Since 

 that work was completed the Glamorgan County Council 

 have forwarded to the Rothamsted Experimental Station 

 samples of 32 varieties of potatoes immune from wart disease, 

 and these have been analysed in the Rothamsted laboratories 



* Obtainable from Messrs. Harrison & Son, St. Martin's Lane, London, 

 W.C. 2, price 25. A note on the Report was published in this Journal, October, 

 1919, p. 741. 



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