18 MISS A. BATESON AND MR. F. DARWIN ON THE EFFECT OF 
was tried; but no effect on the “ growth” of the pith was ob- 
served. This is contrary to what might have been expected; 
since camphor is generally considered to have stimulating effects 
on plants*. 
5. Effect of Ammonia. 
Weak solutions of ammonia were found to have a well-marked 
stimulating effect. These solutions were prepared by diluting 
the Liquor Ammonis Fortior of the British Pharmacopeia, 
which contains 32°5 per cent. gaseous ammonia. The auxano- 
meter-lever was used to estimate the rate of growth. 
The solutions employed contained percentages of the liquor 
varying between 05 and 2:4 per cent.; and within this range 
acceleration was produced. The strongest solution employed 
was 2'4 per cent.; and this did not cause any contraction such 
as was produced by the higher percentages of ether. 
The following Table shows the amount of acceleration pro- 
duced :— 
Strength Amount 
of of 
solution. &eceleration. 
O°5 ..uuuuuueoeessss, 100 : 145 
Oy A ce. 100 : 169 
19 ..................-. 100 : 108 
2:0 .......eeeeeeeernee No effect. 
20:3... 100: 121 
» re 100 : 125 
2A ...Luuuuuueeseesss s. 100: 129 
The experiments are given in detail below. 
Exp. 16.—July 31, 1886. Jerusalem-Artichoke pith; with 
auxanometer-lever. 
Times of « " Times of « » 
observation. Rate of “growth. observation. Rate of “ growth. 
P.M. P.M. 
In water. 5.12 ............ 77 per cent, 
56  ......... 476 ammonia 
416 526 
384 476 
370 434 
370 5.4 ............ 416 
BB... 333 5.7. ............ 232 
$22 
Result: acceleration. 
* See Darwin's ‘ Insectivorous Plants,’ p. 209. 
