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Show 234 CIRCU1\1NUTATION OF LEAVES. CHAP. IV. As the evening rise and the early morning fall wore unusually large, the angle of the petiole above the horizon was ~casured at the two periods, and the leaf was found to have nsen 19° Fig. 100. 1· Cl~ ~ ~~ \.~ :" . .......... -~----~·~<.::.····-... ~ .\ ' ./~// ) /1/ I ,/ 'i ~YS'a.m.B>il ' // ·6~4.5'tt.'!n . 1!Cfo f 7 1 ~ 1 July 2nd to Vioia .faba · circumnutation of leaf, traced rom · ;:~ P.ll • • f the 10J.1' 5 • fl 7~ · h s rom A.M. 4th. Apex of the two tem1inal lea ~ts 4 mc .. e .. nl scale. vertical glass. Figure here reduced to two-thuds of onglll Temp. 17°-18° C. 23° 30' between 12.20 P.M. and 10.45 P.M., and to have fn,llen . 1 c 11 ·na roorn1ng. between the latter hour and 10.20 A.M. on t 1e 1o owi ~ b se The main petiole was now secured to a stick close to the a CHAP. IV. DICOTYLEDONS. 235 of the two terminal leaflets, which were 1·4 inch in length; and the movements of one of them were traced during 48 h. (see Fig.lOl). The course pursued is closely analogous to that of the whole leaf. The zigzag line between 8.30 A.M. and 3.30 P.M. on the second day represents 5 very small ellipses, with thch· Fig. 101. J Y1C,a tfc' dxJ. • eire t t' f 1 • umnu a Ion o one of the two terminal leafl ets the main ~~h.o e;aving been seem·~~' traced from 10.40 A:M· July 4th to'10.30 A.M. red d pex of leaflet 6§ mches from the vert1eal glass. Tracing here uce to one-half of original scale. Temp. 16°-18° C. flooln! ger axes dl ·~u e rent1 Y di·r ected. From these observations it a w~~~~~at both ~he wh~le !eaf and the term~nalleaflets undergo and fallin rked ~a1ly penodiCal movement, rising in the evening whilst in gt dun~g the latter part of the night or early morning; round th he middle of the day they generally cil:cumnutate e same small space. |