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Flora 1879 Carl Kraus

Beiträge zur Kenntniss der Bewegungen wachsenden Laub- und Blüthenblätter

p 66 The cir For the view that the difference between upper & lower side is only slight especially in the leaves of Chenopodium album the following circumstances speaks; viz that these leaves in at an advanced age direct themselves accurately towards (or according to?) the sun, while younger leaves simply bend back in increased light without respect to its direction. Older leaves behave in this respect like symmetrical stems of Chenopodium Cannabis Helianthus tuberosus &c which are most delayed in growth on the side on which the sun strikes them so that they take up positions which follow the sun. ……….

[Movement in plants, p. 250: "(24.) Cannabis sativa (Cannabineae, Fam. 195).—We have here the rare case of leaves moving downwards in the evening, but not to a sufficient degree to be called sleep.*

* We were led to observe this plant by Dr. Carl Kraus' paper, 'Beiträge zur Kentniss der Bewegungen Wachsender Laubblätter,' Flora, 1879, p. 66. We regret that we cannot fully understand parts of this paper."]

p 67 In The following is a proof of the view that differences (not great in comparison to the sensibility) & lower sides cause the capability for movement.

Chenopodium, Stellaria &c lose their periodic movements (even under normal light-conditions) when by much water just that very side which is conquering is energetically favoured & thus the difference in growth is increased

[Movement in plants, p. 318: "Carl Kraus has also lately insisted† on the great influence which the quantity of water absorbed has on the periodic movements of leaves; and he believes that this cause chiefly determines the variable amount of sinking of the leaves of Polygonum convolvulus at night; and if so, their movements are not in our sense strictly nyctitropic.
† 'Beiträge zur Kentniss der Bewegungen,' etc., in 'Flora,' 1879, pp. 42, 43, 67, etc."]

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69)

The sensibility increases with increased growth, & also the difference between the upper & lower sides diminishes, so that the movement can begin "at a different age of the leaves" (ie I suppose in leaves of various ages) If the sensibility is so too slight in the hyponastic state & the difference between the two sides too great then with increased light that (Krümmung) bending? (ie I suppose the tendency to bend) towards the stem diminishes without causing any opening. Therefore is always a possibility of periodic movement when the leaf has become epinastic

If illumination can well delay the upper side of a leaf in this condition then with increased light* bending upwards will occur (*here comes in an unintelligible remark "the opening bending will be flattened and &c"). In epinastic leaves the upper side is the more sensitive therefore they shut by day open by night. The same conditions hold for the relation between upper & lower side in sensitive joints. Here also in decreased illumination that side will conquer, which at the beginning of the capability for movement is the strongest in the already described manner

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p 70) young leaves of Cannabis sativa offer a case of periodic movement which appears first in the epinastic leaves, but is here unable to influence the upper side so far as to re preserve the position. In the evening they bend energetically down & during the stalk gets more & more straight. The leaves which are still hyponastic show no movement. Epinasty is so prepotent that no conditions of illumination can reverse the relationship in length in favour of the under side. The leaves relax during the day at night they are tense. on rainy (c) sunny as well as sunny (b) rainy days

Kraus

Keep for chapter on movement of Leaves