[80]

Trifolium subterraneum circumnutation & sleep of a terminal leaflet.— July 4th 1878

Tracing 10 1/2 time actual movement. ie. the extreme point thus much exaggerated

Trifolium termin

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

F. 154.

6. 45' a.m July 4th

8º. 30' a.m

10. 15 a.m

Point when  Horizontal  apex of leaf stood horizontal (—H)

10. 55' a.m.

11º.12' a.m

11º. 30'

12º

12. 45'

1º. 21'

2. 12'

3. 3'

4º

5

5. 26'

 P.m  6º

nocturnal course.

6º 45' a.m. July 5'

8º. 30' a.m

9º 15 a.m 5th

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.]