400 BOTANICAL GAZETTE [ DECEMBER 
likely to increase, and abnormally rapid growth to decrease the 
turgor, than to be caused by variation in the latter. 
In Stange’s work, the substratum was merely a physical 
agent of varying concentration. But few salts were used, and 
no essential difference was observed in their action. Beyond a 
suggestion by Benecke ", that the turgor may be caused by the 
presence of sodium as well as by that of potassium, and that 
the continual acquisition of the former probably serves such 
“secondary” functions, the relation between the chemical nature 
of the substratum and the turgor has never been considered. 
To assist in clearing this untrodden field, my investigation was 
undertaken. 
It was hoped in beginning this study that a considerable 
number of chemical elements would be made to show some 
direct influence on turgor. But as the tables well show, this 
hope was not realized. With the exception of potassium, and 
in one case, perhaps of NO,, the removal of any food constituent 
did not tend to depress the turgor, or if it did, it stopped the 
growth so quickly and effectively that the turgor rose. Failure 
to get evidence on the question in hand is then added support 
for the thesis already referred to,” that growth regulates turgor 
more decidedly than turgor growth. 
Methods— All the plants used as subjects of experiment 
were grown in water culture, in glass jars, protected from the 
light by heavy drying paper. The covers of the jars were wood, 
bored nearly through with a large auger, the rest of the way 
with a small one, furnishing an excellent support for the 
seeds. The jars for most of the experiments were of a little 
less than three liters capacity, larger ones of eight liters being 
sometimes used. During the time that the experiments lasted, 
warum nicht in solchen Lei weniger eng an vitale Functionen gekettet, 
mehr als formale Bedingungen des Lebens aufzufassen sind—nahe liegt ¢s ale 
z. B. an osmotische Leistung denk z. B. Natriummolekel fiir das Kalium em” 
springen kénnten. 
™ Copeland, loc. cit. 
ie a 
