R. Newton 15 



The ratio of the value P — P, to the corrected vahie for specific con- 

 ductivity ( X 10^) is given in the last column of the table. This should 

 be a constant in case the cell sap electrolytes in each variety were identical 

 in composition, and the effect of solutes other than sugars on the mobility 

 of the ions can be considered equal for all varieties. The ratio of P — P., 

 to the observed value for conductivity is given in the adjoining column, 

 in order that the effect of the correction for sugar content may be seen. 

 For the earlier collection the ratio, based on the corrected values for 

 conductivity, varies from 0-96 to 1-07, and averages 1-00, but for the 

 later collection it falls off somewhat, ranging from 0-73 to 0-91 with an 

 average of 0-80. Possibly the heating of these later samples to lOO^ C. 

 had released ions which would otherwise have remained adsorbed by 

 cell colloids, thus increasing somewhat the value of A', though Mason's 

 results (28, Table VI) suggest that such an increase would probatily 

 have been very small. In any case, the diminution in the value of P — P, 

 in the later collection is so decided as to make it unlikely that the possible 

 disturbing factors introduced by the heating could account entirely for 

 the failure of K to diminish correspondingly. Furthermore, the content 

 of soluble protein (see Table V) is small and relatively constant, and the 

 hydrogen-ion concentration is Cjuite constant, so that the possibility 

 of any considerable variation in conductivity due to protein salts and 

 organic acids may be excluded. The evidence suggests that substances 

 other than electrolytes, and variable in nature, must contribute somewhat 

 to the quantity P — P^, or in other words that sugars are probably not 

 the only non-electrolytes which contribute to the osmotic values. 



The amino nitrogen, water-soluble nitrogen and total nitrogen in per- 

 centage of green and dry weights are given in Table V. The percentage 

 of dry matter content is also included. It cannot be said that any of the 

 figures exhibit a marked correspondence to differences in degree of 

 hardiness. The increase in the water content of the collection of Decem- 

 ))pr is accounted for by a mild rainy period of some days" duration 

 which occurred during the previous week. It has been remarked already 

 that Kanred killed somewhat more than the other varieties during the 

 season of this experiment, and this variety was lowest in dry matter 

 content. However, in the hght of the evidence already presented, it 

 seems possible that our view of the nature of the correlation between dry 

 matter content and hardiness may require modification. A smaller 

 water content is naturally associated with the smaller cells and denser 

 tissues characteristic of the slower growth in late autumn, so that in 

 general hardened tissues would be expected to contain less moisture than 



