[11]

Bignonia Tracing I. after 10' a.m on July 20th

[data not transcribed]

convergent by cot

[12]

Window

Right Hand Tendril of

Bignonia capreolata Anheliotropism

19' & 20 July

Tracing II.

[data not transcribed]

converging by cots

[12v]

40

Introduction

raised from such seeds were dwarfed. I was therefore careful to give an amply sufficient supply of pollen, and generally covered the stigma with it; but I did not take any special pains to place an equal amount on the stigmas of the self-fertilised and crossed flowers. After having acted in this manner during two seasons I remembered that Gärtner thought that an excess of pollen was perhaps injurious; and with some animals it has been proved by Spallanzani, Quatrefages and Newport* (*Transaction Philosophical Soc. 1853 p. 253-258) that with various animals an excess of the seminal fluid entirely prevents fertilisation. of the ova. It was therefore necessary to ascertain whether the fertility of the flowers was affected by applying a rather small and a extremely very large quantity of pollen to the stigma. Accordingly a very small mass of pollen-grains was placed on one side of the large stigmas of 64 flowers of Ipomoea purpurea: and a great mass of pollen

[Cross and self fertilisation, pp. 24-25: "Naudin also found in the case of Mirabilis that if only one or two of its very large pollen-grains were placed on the stigma, the plants raised from such seeds were dwarfed. I was therefore careful to give an amply sufficient supply of pollen, and generally covered the stigma with it; but I did not take any special pains to place exactly the same amount on the stigmas of the self-fertilised and crossed flowers. After having acted in this manner during two seasons, I remembered that Gärtner thought, though without any direct evidence, that an excess of pollen was perhaps injurious; and it has been proved by Spallanzani, Quatrefages, and Newport,† that with various animals an excess of the seminal fluid entirely prevents fertilisation. It was therefore necessary to ascertain whether the fertility of the flowers was affected by applying a rather small and an extremely large quantity of pollen to the stigma. Accordingly a very small mass of pollen-grains was
* 'Kentniss der Befruchtung' 1844 page 345. Naudin 'Nouvelles Archives du Museum' tom. i. page 27.
† 'Transactions of the Philosophical Society' 1853 pages 253-258.
placed on one side of the large stigma in sixty-four flowers of Ipomoea purpurea, and a great mass of pollen over the whole surface of the stigma in sixty-four other flowers."]