[80]

nocturnal poin course

Trifolium subterraneum circumnutation & sleep of & terminal leaflet.—

July 4th 1878

Tracing 10 1/2 times actual movement ie. the exterior point thus more exaggerated

[data not transcribed]

F. 159. H Horizontal apex of leaf Point when leaf stand horizontal

1/2 scale: by cutting off top above pencil line & adding curved dotted arrow to show course, the block will just go in my page.

no lettering, except (H) to short horizontal line on left-side

I fear this diagram will be difficult to do the lines are so close

697

Chap. E 10

glands on their leaves, petioles, phyllodia, stipules, bractiæ, flower-peduncles and or the outside of the calyx; and these glands secrete minute drops of a sweet fluid which is eagerly sought for m by sugar-loving insects, such as ants, hive-bees and wasps. In the case of the glands on the stipules of Vicia sativa, the secretion manifestly depends on changes in the sap consequent on the sun shining brightly; for I repeatedly observed that as soon as the sun was hidden behind clouds the secretion ceased and the hive-bees left the field; but as soon as the sun broke out again they returned to their feast.* (3) I have observed an analogous fact with the secretion of true nectar E the flowers of Lobelia ramosa.—)

On the other hand Delpino maintains that the power of secreting a sweet fluid by any extral floral organ has been in every case specially gained for the sake of attracting ants and wasps so as to defend the plants from enemies; but I have never seen any reason to believe that this is so with the three species observed by me, namely Prunus laurocerasus, Vicia Sativa and

[Cross and self fertilisation, pp. 402-4.]