[57-59]

Virginian Tobacco

Circumnutation of leaf — stem secured

July 10th to 13th

F 168 [data not transcribed]

(Used)

Nicotiana Tabacum: circumnutation & sleep of leaf, 5 3/8 inch in length, traced on vertical glass from 3° P.m July 10th to 8° 10' a.m 13th. Apex of leaf 4 inches from glass— Plant illuminated from above. Temp. 17 1/2 — 18 1/2 C

reduce to 1/2 of origin scale

[59v]

36

Introduction

judge by the appearance of the plants and by comparing as was done their fertility with that of neighbouring uncovered plants, it would not have vitiated my experiments; as for in all the more important cases the flowers were crossed as well as self-fertilised under a net, so that they were treated in this respect exactly alike.

As it is impossible to exclude such minute pollen-carrying insects as Thrips, flowers which had been werefertilised with their own pollen may sometimes have been crossed by these insects with pollen brought from another plant flower on the same plant; but as we shall hereafter see that a cross of this kind does not produce any effect or at most only a slight one. But When two or more plants were placed near one another under the same net, as was often done, there is some real though not great danger of the flowers which had been were self-fertilised having being afterwards crossed with pollen brought by Thrips from