422 



BULLETIN No. 127. 



[August, 



In order to find the proportion of cortical layer and inner medul- 

 lary layers, the authors cut the potatoes in half through the long 

 diameter, marked the line of demarcation of the two layers on 

 paper and weighed the corresponding slips.* The average of all of 

 the good eating varieties in proportion of cortical layer to inner 

 medullary layers was 100:121.5, while the proportion in the coarse 

 varieties was 100:140.4. The actual cooking tests bore out their 

 opinion of the relative cooking value of the varieties as expressed 

 in their classification, and they concluded that chemical composition 

 could not be used as a basis of selection for cooking value. 



In 1905 Gilmore (44) published an excellent paper in which he 

 tentatively concluded that the culinary value of the potato depended 

 not so much upon its chemical composition as upon its anatomical 

 and perhaps its physiological structure. 



EXPERIMENTAL 

 COMPOSITION OF DIFFERENT PARTS 



The first object in this work was to see if American varieties 

 and especially if within a variety, the table quality is dependent 

 upon the total nitrogen content. 



The two varieties Rural New Yorker No. 2 and Carman No. 3 

 were selected as being representative popular varieties. Careful 

 mechanical separations of the different zones were made in five in- 

 dividual potatoes of each variety, after the manner of Condon and 

 Boussard. Dry matter was determined at 104 degrees C in a cur- 

 rent of hydrogen, and total nitrogen was determined by the regular 

 Kjeldahl method, as were all similar determinations here reported. 

 The averages of the results of each variety are shown in the fol- 

 lowing table : 



TABLE 3. COMPOSITION OF PARTS OF THE POTATO 



*This method does not show the correct relation. If the potatoes were considered as sper- 

 ical, the relation would be (whole dia meter) 3 -(medullary diameter) 3 : (medullary diameter 3 ). 



