70 STUDIES IN THE VEGETATION OP THE STATE 



ing the period of drought from one of the sources indicated 

 above. Such results were omitted in the general average 

 for each species. 



It may be well to question the accuracy of the results 

 obtained in calculating the limit of physiological water, 

 where the water in the dying plant was less than 20 per 

 cent in grasses and less than 25 per cent in other plants, 

 since it is probable that most plants have ceased to obtain 

 any water from the soil by the time there is less than 30 to 

 50 per cent of water in their tissues. This is a problem 

 for further investigation since the results indicate that there 

 is a variation in the amount of water in the plant when it 

 dies, not only in different species, but also in the different 

 plants evea if taken at the same age. Such variation is 

 probably caused by differences in the structure of plants 

 growing under different physical conditions. The whole 

 matter is also inseparably connected with the vigor of the 

 plant and its adaptability to its surroundings. 



