May 1. 1916 Effect of FusaYium spp. on Potato Tubers 



185 



termined by the usual methods ^ in dry ether-extracted samples which 

 had been ground. For the percentage of dry matter the sliced-up 

 samples were placed in glass-stoppered weighing bottles and covered 

 with alcohol. The alcohol was then driven off and the samples dried 

 to constant weight. All data were calculated to the original wet weight 

 of the potato used. The potatoes used in the experiment were smooth 

 white potatoes usually purchased at the local market. The cultures 

 of fungi used in the experiments were subcultures from Carpenter's cul- 

 tures of F. oxysporum 2,Z95 and 3315; F. mdicicola 31 13 and 3319, and 

 F. coeruleum 3501. 



EXPERIMENTATION 



To determine the amount of variation in content of the different com- 

 pounds in the four quarters of the potato, series of preliminary analyses 

 were carried out. In these the potato was sampled in the usual way, 

 except that the portions were sliced immediately and prepared for 

 analysis. The results of these analyses are shown in Tables I to VI. 



Table I. — Reducing sugar and sucrose content of quarters of sound potatoes 

 [Expressed as percentage of wet weight] 



Potato No. 



Reducang sugar. 



Quarter 

 A. 



Quarter 

 B. 



Quarter 

 C. 



Quarter 

 D. 



Sucrose. 



Quarter 

 A. 



Quarter 

 B. 



Quarter 

 C. 



Quarter 



43 

 44 

 46 



49 

 87 

 88 



105 



o. 10 

 .06 



•17 

 . 02 

 o 



O. II 



.06 

 • 14 



. 02 



09 

 07 

 14 

 03 



O. II 



.06 

 .19 



. 02 

 o 

 o 

 o 



o. 04 



.04 



. 02 



•03 

 .07 

 .06 

 • 05 



,04 

 03 

 03 

 07 



OS 



08 



o. 04 



• 03 

 .04 



• 03 

 .07 

 .06 

 .07 



o. 02 



• 03 

 .04 

 .04 

 .06 



• 05 

 .06 



Table II. — Starch content of quarters of sound potatoes determined by the direct acid- 

 hydrolysis method 



[Expressed as percentage of starch, wet weight] 



Potato No. 



Quarter A. 



Quarter B. 



Quarter C. 



Quarter D. 



70. 

 47- 

 50- 



17.88 

 16.43 

 15.04 

 18.56 



19.52 



15-35 



16. 04 



17. 16 



17.07 

 15.64 

 16. 00 

 16.54 



17. 26 

 16. 04 

 14. 50 

 17.27 



Table III. — Pentosan content of quarters of sound potatoes 

 [Expressed as percentage of wet weight] 



Potato No. 



Quarter A. 



Quarter B. 



Quarter C. 



Quarter D. 



19. 

 28. 



47- 

 207. 



0.51 



•37 

 .41 

 •51 



0.43 

 •35 

 .40 

 .48 



o. 46 



•35 

 •37 

 .48 



48 



37 

 40 



51 



> Wiley, H. W., ed. Op. cit. 



