Senile Changes in Leaves of Certain Plants 



341 



TABLE 55. 



Amount of Water Imbibed by Leaf Powder from Vines with from 6 to 



8 AND FROM 20 TO 25 RiNGS 





KOH 



(cubic 

 centimeters) 



Oxalic 



acid 



(2 grams of) 



Height of 



column 



(millimeters) 



Weight of 



imbibed 



water 



(grams) 



Percentage 

 of imbibed 



water 



Yomig leaves 



1 



2 



S.'.'.'.'.'.'.'.'.'. 



Old leaves 



1 ' 



2 



3 



Young leaves 

 1 



2.00 

 2.00 

 1.95 



1.40 

 1.35 

 1,30 



2.80 

 2.80 

 2.50 

 2.00 

 2.00 



1.60 

 1.60 

 1.60 

 1.60 

 1.60 

 1.60 



.02 mol. sol. 

 . 02 mol. sol. 

 . 02 mol. sol. 



.02 mol. sol. 

 .02 mol. sol. 

 .02 mol. sol. 



. 02 mol. sol. 

 . 02 mol. sol. 

 . 02 mol. sol. 

 .02 mol. sol 

 .02 mol. sol. 



.02 mol. sol. 

 . 02 mol. sol. 

 . 02 mol. sol. 

 .02 mol. sol. 

 .02 mol. sol. 

 . 02 mol. sol. 



53 

 53 



54 



48 

 46 

 42 



0.9968 

 0.9298 

 1.0018 



0.9458 

 0.7948 

 0.8168 



0.9588 

 0.9852 

 0.9847 

 1.0194 

 0.9141 



0.6076 

 0.6692 

 0.7512 

 0.5875 

 0.8054 

 0.9938 



498.4 

 464.9 

 535.9 



472.9 

 397.4 

 408.4 



474.4 



2 





479.1 



3 



492.4 



4 





509 7 



5 





457 1 



Old leaves 

 1 





303.8 



2 





339.6 



3 





375.6 



4 





293.8 



5 . 





402.7 



6 





496.9 









General average of percentage of imbibed water for young leaves 489 . per cent 



General average of percentage of imbibed water for old leaves 387 . 9 per cent 



The substance of the younger leaves has a greater inherent property of 

 imbibing water than that of the older leaves. Some of this difference, 

 no, doubt, is due to the greater proportion of vascular tissue present in 

 the older leaves, but the difference in percentage of imbibition seems to 

 be greater than would be caused by the difference of vascular tissue. This 

 greater capacity of imbibing water, if present in hving leaves, must play 

 a part in the distribution of substances among the cells, as well as directly 

 affect other activities of the protoplasm. 



OTHER EVIDENCES OF SENILITY 

 The investigations on veinage, photosynthetic activity, respiration, 

 and imbibition point to the. conclusion that leaves of old vines have suf- 

 fered senile degeneration and that they are less efficient organs than leaves 

 of young plants. Since such a veiy marked character as veinage is al- 

 tered by age, it is probable that other differences exist between leaves of 



