Turgor and of Temperature on Growth . 371 
the swelled seeds are placed in the sawdust. About one 
day before the maximum is reached, protuberances indicate 
the internal formation of lateral roots, which burst through 
and begin a rapid growth, the oldest attaining an average 
length of about 10 mm. by the time the primary root has 
reached its maximum rate. From this time on, the demands 
of the laterals cause the curve to fall. 
TABLE I. 
Period. 
Growth 
per hr. 
Medium. 
Hours. 
Min. 
I 
45 
0 
>rj 
6 
mm. 
Water 
J 7 
OO 
O ' 75 
7? 
99 
6 
OO 
0.65 
99 
99 
17 
15 
0.65 
>> 
9 9 
23 
15 
0.80 
9 9 
99 
24 
OO 
0.97 
99 
9 9 
25 
30 
0-98 
99 
99 
47 
30 
0.72 
99 
99 
24 
30 
0.56 
99 
47 
45 
0.58 
99 
99 
5 ° 
OO 
°*59 
99 
99 
Passing now to the consideration of the effect of changes of 
concentration of the medium on growth, it may be said, 
a priori , that two factors enter into the question; (1) the 
length of time during which the objects are exposed to the 
action of the various culture-mediums, and (2) the degree of 
concentration of the same. 
In order to roughly determine what degree of concentration 
could be endured, and for how long, seedlings of Vicia Faba 
were brought into saltpetre solutions of 3-0, 1-5, i-o, and 0-25 
per cent, respectively. Three per cent, was found to be 
speedily fatal in its action. If the exposure in 1-5 per cent, 
was for a short time only, the transfer to water was followed 
tardily by returning growth ; if the exposure was prolonged, 
