RECORD: Darwin, C. R. & Francis Darwin. 1878.07.23-29. Trifolium subterraneum / Draft of Cross and self fertilisation, folios 732, 738 and fragment. CUL-DAR209.11.242-244. (John van Wyhe ed., 2002-. The Complete Work of Charles Darwin Online, http://darwin-online.org.uk/)
REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 7.2023. RN2
NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volume CUL-DAR209.11 contains material for Darwin's book Movement in plants (1880). The text of the draft corresponds to Cross and self fertilisation, pp. 457, 425 and 429.
[242]
Long straw — Roof
Young young Flower, head vertical
Trifolium subterraneum
July 23d
8° 40' a.m.
9. 15 far to left & little from me Trifolium subterraneum
10. '17' from me & to left , immense distance
11. 8' com back nearly parallel to right & to me
12. 25— same course— Clearly circumnutates, whilst flower young
1. 30' to left
2. 55 far to left
4° do — same course
5 turned at rt angles to me
6° a little back & to right.
7°. 15. to the right rather short ways
9 to right & to me
10. 40' to right
24th 6° 40' ......
8° 7' to me & to right some distance
8. 30 to right
9 30 do
10 25 same course
11. 50 do
1° to Right & to me
2° far to left. back.
3° same course
4° to me
5° to left & from me
6° P.m to me
7. 15 same course
freed the shoot 7° 15
⊡ ..................
9° to right & to me far
10. 30' on frame
25th 6°. 45 straw a little above Horizon
7° on vertical glass
7° 35 to left
8° up !
8° 36' to left & up
9° to left & risen
[242v]
which has been differentiated by exposure to different conditions or through spontaneous variation. But the analogy fails when we turn turn to the negative or weak effects of pollen from one species, for it does not appear that although some substances which are extremely dissimilar, for instance, carbon and chlorine, have a very feeble affinity for each other, yet it cannot be said that the weakness of the affinity depends in such cases on the extent to which the substances differ. It is not known why different differentiation is necessary or favourable for the chemical attraction affinity or visible any more or union of two substances, any more than for the fertilisation or union of two plants.)
[243]
Trifolium subterraneum (Black Paper)
Black Paper
July 24' 8° 30' a.m first dot ↓.
9° 30' to me & to right
10. 25 to me, straight
11. 50 little to Right
1° to left back & parallel — (certainly circumnutating)
2° from me & little to left
3° back to me [sketch]
4. to right a little
5 same spot
6° from me
7. 15 little to left
25 9° 15' a. m cut stick free
9.° 25' mark [sketch]
10. 27
but was disturbed
10. 45'
11. 30' from me or to left ie back & parallel
12° to right
1° from me & to left.
3 to right & to me
4. 30 from me; (but then I accidentally lifted up flower by touching a leaf)
6°. to right
7. 15 from me
9. nearly same spot: 10° 40' do
26th 6° 40' .......
8° to me
9' 10' nearly same spot
[243v]
732 3 (18
Ch XI
visited by three bees In nineteen minutes each every flower on a small plant of Nemophila insignis was entered visited twice. In one minute six flowers of a Campanula were entered by a pollen-collecting hive-bee; and bees when thus employed they work slower than when sucking nectar. Lastly, seven flower-stalks on a fruit plant of Dictamnus (213) fraxinella were observed on the 15th of June 1841 for during ten minutes; and they were visited by 13 humble-bees each of which entered many flowers; on the June 22nd the same flower-stalks were visited within the same time by 11 humble-bees. This plant bore altogether 280 flowers and from the above data, taking into consideration how late in the evening humble-bees work, each flower must have been visited at least 30 times daily, & the same flowers keep open during several dail days. The frequency of the visits of bees to the same flowers, is also sometimes shown by the manner in which the petals are scratched by their hooked tarsi of the bees; I have
[244]
continued
Long Straw was on roof now on temporary Vertical glass
Trifolium subterraneum
9°. 30 up
10. 15 to left
10. 50 down
11. 30 do — 19° above Horizon
19
71
12° vertically down
1° up again
3° considerably up.!
4 25 up {I see straw attached to 1 flower & it is this which is rising, whilst peduncle is more arched down, so that if straw had been attached to it — it wd have been 45° beneath horizon
6° up & to left
7. 15 to left & little down
9 down, straight
10. 40 down
(Used)
26th.— 6 — 37° ......
8°. 5 up & to right
9 10 up & to left
10. .35 up.
12 — much up
{1. 45. very little up—
3° nearly same spot
4. 35 fallen a little
6° .a little down & to left
9° down & to left
27th 6° 40' ......
9° am ⨀ on vertical glass
28th. 8° 30 am up
29th 8° a.m. ⨀
} went on circumnutating
Straw seem to have nutating action
[244v]
738 (24
Ch XI
of the two. My son remarks "It is difficult to say how the bees could have acquired this habit. Whether they have discovered the inequality in the size of the nectar-holes in which sucking the flowers in the proper way, and have then utilised this knowledge in determining where to gnaw the hole; or whether they have found out the best situation by biting through the vexillum standard at various points, & have afterwards remembered its situation in visiting other flowers. But in either case they show a remarkable power of making use of what
Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
File last updated 8 December, 2025