302 BOTANICAL GAZETTE [ NOVEMBER 
plasmolyzed before death ensued, sometimes not. Of the four 
simple solutions one appeared to affect the plant as much as 
another. The table shows the general result of the experiments 
almost graphically. In the higher concentrations the larger 
numbers appear mainly in the middle of the series, in the columns 
headed Many, while the third and eighth columns are nearly 
vacant. Passing to higher concentrations this gradually changes, 
until, in the highest, the reverse is true. The following conclu- 
sions may be drawn from these data. 
1. Nature of the stimulus—The effect of a solution of any 
given osmotic pressure upon the plant is both qualitatively and 
quantitatively the same, no matter what the chemical nature of 
the solution may be. If this effect were due to change in the 
amount of any one salt, then this fact would have appeared in 
the course of the experimentation, for my various solutions were 
devised to test this point. So we have eliminated, as far as the 
palmella form is concerned, the possibilities designated under I, 
a,b,c, and 2,6, page 295. The stimulus cannot be of a chemical 
nature, nor can it be physical and depend more upon tag aah 
ence of one salt than upon another. Also, we have eliminat 
3 from among the possible primary stimuli. Consider : 
facts shown, it is impossible that the external stimulus S208 : 
iment of certain 
be either physical, with the necessary accompan a 
chemical factors, or yet chemical, with the necessary acreye 2 
ment of certain physical ones. It is, however, nae : 
but probable that the external and primary physical “43 
may cause an internal and secondary chemical one. a a 
lies beyond the scope of the present research. Thus ene 5 
driven to accept 2, a as the truth in the matter, and to 
that the response of the organism is determine 
and never, as far as my experiments have gone 
stimulus. The effect of osmotic pressure upon t upod 2 
form is a double one. I shall consider, first, the eich 
vegetative growth, and second, that upon reproduct! 
2. Response in vegetative growth.—In my leat ae 
solution (pressure 96 V X 10") the mode of cell divisiOv” 
on. . 
oncentratee 
