i86 



Journal of Agricultural Research 



Vol. VI. No. s 



Table IV. — Galactan content of quarters of sound potatoes 

 [Expressed as percentage of wet weight] 



Table V. — Crude fiber content of quarters of sound potatoes 

 [Expressed as percentage of wet weight] 



Potato No. 



Quarter A. 



Quarter B. 



Quarter C. 



Quarter D. 



102 

 210 

 211 



0.50 



•47 

 .40 



0.59 

 •47 

 .41 



0.48 

 •47 

 •39 



0.47 

 .44 



•36 



Table VI. — Dry matter in the quarters of sound potatoes 

 [Expressed as percentage of wet weight] 



Potato No. 



Quarter A. 



Quarter B. 



Quarter C. 



Quarter D. 



118 

 119 

 120 

 138 

 143 



20.86 

 20. 70 



19-73 

 24. 12 

 24. 19 



19.96 

 20. 96 

 20. 23 



24. 58 

 22.37 



21.95 

 19. 16 

 21. 42 

 25-36 

 24. 81 



17.78 

 19.77 

 20.73 

 24. 80 

 22. 82 



Tables I to VI show that there is considerable variation in the percent- 

 age of some of the compounds in different quarters of the same tuber, 

 though usually the actual difference is not great. It is noticeable that 

 two portions of the same tuber are more nearly alike in composition than 

 samples from different potatoes. The method, therefore, which involves 

 the comparison of the content of two quarters of the same potato is 

 more accurate than one based on a comparison of the composition of 

 two different potatoes. The experiments in which sound and rotted 

 quarters were analyzed to determine the effect of the fungi upon the 

 potato show that data from which definite conclusions may be drawn 

 can be obtained by this method. 



Inasmuch as the mycelium of the fungi was present in the rotted por- 

 tions of the potatoes, it was of interest to determine what influence the 

 compounds elaborated by these fungi would have on the apparent com- 

 position of the tuber. Quantities of mycelia of the two fungi F. radicicola 

 and F. oxysporum were accordihgly grown on potato extract. This 

 medium was prepared by boiling sliced potatoes until they were soft, 

 filtering the extract through cotton, and sterilizing it in suitable flasks. 



