[71]

Apheliotropm Mustard — Caustic

In the experiments on Ap 29 & 30, 14 15 were causing cauterized; & of these 12 were not apheliotropic, 2 were apheliotr & one doubtful

Caustic 18 [+] 23 [=] 41

Of All the 18 control roots were apheliotropic

The cauterized roots grew well— ie increased by from 5 to 7 mm in 8 or 9 hrs—

Ap 29 was bright sunshine, Ap 30 was "gleams of sun"

25 [+] 16 [=] 41 16

In the experiments Sep 7, 12 & 13, 41 roots were cauterized of these 25 were apheliotr, 16 were not so. All 20 23 controls were apheliotr except 2 doubtful & apheli ones. These jars were put to a North light, but the temperature was sufficiently high viz 16 C in the morning

Adding the Sept & April experiments together there are 53 54 cauterized ones whose of which 25 are Aph, 28 not so, & one doubtful. Of 41 controls, 39 are aphelio: & 2 doubtful

On Sep 12 & 13 the seedlings were examined in the evening & there was neither heliotr of the stems nor apheliotr of roots, the curvatures recorded in above experiments appeared during night & the following morning; the seedlings were in both experiments examined between 10 & 11 on the morning after they had been cauterized

They were all grown in sawdust till taken out to be cauterized & grown in water in glass jars

[71bis]

In the April experiments the bending place was at about 4 mm from tip.

The blackened tips were about 1/2 mm, or rather more eg 0.7 mm

I am not sure about the colour of the tips

[71v]

[notes in Darwin's hand, not transcribed]