22 MISS A. BATESON AND MR. F. DARWIN ON THE EFFECT OF 
8. Effect of Nitric Acid. 
The effect of nitric acid was not very evident. Five experi- 
ments were tried with this acid. The percentages used were 
1 per cent. in three of these experiments, and ‘8 per cent. and 
-54 per cent. in theothertwo. On one occasion 1 per cent. had a 
markedly stimulating effect ; but this was not confirmed by the 
other two experiments; for in one of these 1 per cent. caused & 
marked retardation of the rate of growth, and in the other it 
eaused a sudden contraction, followed immediately by further 
growth; °8 per cent. had no marked effect; and ‘54 per cent. 
caused a distinet retardation. 
"54 per cent. ............... 100: 44 
S, ,. 0 0 sese 100 : 52 
| , —ee—————- 100 : 259 
Le. gy | eneeett 100 : 44 
l , ne Contraction. 
9. Effect of Carbolic Acid. 
The percentages used were 0*5 per cent., 1 per cent., and 3 per 
cent. The two lower percentages did not appear to have any 
effect ; but 8 per cent. caused a contraction of the pith. In one 
experiment with 3 per cent. carbolic the contraction was very 
rapid; and the pith, on being freed from the auxanometer, was 
flaecid, and did not recover its turgidity on being placed in 
water. 
Exp. 24.—Sept. 10, 1886. Jerusalem-Artichoke pith; lever. 
Times of observation. Rate of * growth." Temperature. 
90 
P.M. . 
1210 ............... Tap-water. 16:5 
1211  ................ 105 » 
12115  ................. 105 » 
1218 — eese 113 ^ 
1214 ................. 108 » 
12142 ............... 95 » 
12145 . .................. Siphoned out water. » 
1216 ................. 3 per cent. carbolic » 
acid added. 
1217 ..............-- Began to shorten. » 
Shortened 1 millim. 
1228 .  ..........ee Not flaccid. 
The result is interesting, as showing how rapidly the poison 
takes effect in causing contraction. 
TOR MM a 
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