372 True . — 6 ^ the Influence of Sudden Changes of 
the root-tips died. In solutions of a i-o per cent, concentration 
or less, accommodation and further growth took place. 
That, by a gradual increase of concentration, growth in 
mediums which here proved fatal could take place, is certain 1 . 
Pisum sativum and Lupinus albus were found to be more 
sensitive than Vicia Fab a. Indeed, Lupinus was more strongly 
affected by a 0-25 per cent, solution than Vicia Faba by one 
of i-o per cent. KN 0 3 content. 
Table II shows the average growth of six roots of Vicia 
Faba in a i-o per cent, saltpetre solution for 4 days. Tempera- 
ture 17-0° to 1 8-9° C. 
TABLE II. 
Period. 
Growth per hr. 
Medium. 
Hours. Min. 
30 
*0-2 mm. 
KN0 3 (i%) 
3 
°5 
0 
00 
77 
3 
10 
0*63 „ 
7 7 
0 
0 
i'-. 
062 ,, 
77 
23 
15 
°- 5 2 „ 
77 
24 
15 
o-55 „ 
77 
23 
45 
o-49 » 
” 
* Estimated average contraction. 
In order to obtain approximately the extent of the con- 
traction due to the turgor-reducing action of the KNO a 
solution, a measurement was made 30 minutes after the 
transfer to the medium. Although decimal parts less than 
0-5 mm. are questionably near the limit of accuracy with the 
scale, still the average contraction has been given as estimated. 
It seemed to me that the estimates were nearer the truth than 
either the nearest unit or half unit. A further discussion of 
this feature is reserved for a later part of this paper, where 
the results of measurement with the horizontal microscope 
receive attention. 
1 Stange, loc. cit. 
