TEXDBIL-BEAEEES. 



65 



LEGU]vri]s^os^. — Pisiim sativum . — The common Pea was the sub- 

 ject of a valuable memoir by Datrochet* who discovered that 

 both the internodes and tendrils revolved in ellipses. The ellipses 

 are generally very narrow, but sometimes approach to circles : I 

 several times observed that the longer axis slowly changed its 

 direction, w^hich is of importance, as the tendril thus sweeps a 

 nauch wider circuit. Owing to this change of direction, and 

 likewise to the movement of the stem towards the light, the 

 successive irregular ellipses generally form an irregular spire. 

 I have thought it worth while 

 to annex a tracing of the course 

 pursued by the tipper inter- 

 node (the movement of the 

 tendril being neglected) of a 

 young plant from 8.40 a.m. to 



Fig. o. 



Diagram showing the movement 

 of the upper internodes of the com- 

 mon Pea, traced on a hemispherical 

 glass and transferred to paper; re- 

 duced one-half in size. (Aug. 1st.) 



9.15 



P.K. 



The 



course was 



traced on a hemispherical glass 

 placed over the plant, and the 

 dots with figures give the hours 

 of observation ; each dot was 

 joined by a straight line : no 

 doubt these lines, if the course 

 had been observed at shorter 

 intervals, would have been all 

 curvilinear. The extremity of 

 the petiole, where the young 

 tendril arises, was 2 inches 

 from the glass, so that if a 

 pencil 2 inches long had been 

 in imagination affixed to the 

 petiole, it would have traced 

 the annexed 



figure 



on the 



under side of the glass ; but 

 it must be remembered that 

 the figure is here reduced one- 

 half. Neglecting the first great 

 sweep towards the light or 

 window, the end of the pe- 

 tiole swept a space 4 inches 



win 



2. 10 

 3.11 



h. m. 



8 46 A.M. 





 





4. 11 37 „ 



5. 12 7 P,: 



6. 12 30 



7. 1 



8. 1 30 



n 



»* 



h. m. 

 9. 1 55 P.M. 



10. 2 25 



11. 3 



12. 3 30 



13. 3 48 



14. 4 40 



15. 6 6 



Tt 



J» 



»f 



n 



f$ 





It 



h. m. 



16. 5 2o P.M. 



17. 5 50 



18. 6 25 



19.7 „ 



20. 7 45 „ 



21. 8 30 „ 



22. 9 15 



tt 



ft 



t> 



across m one direction, and 3 inches in another. As a full- 



ffTOWn tendril is conftidpm'hlv nTmvo 9. irj^Ti^a I'n Ifiiifrfli anrl afl thft 



Comptcs Rcndus, torn. xrii. 1843, p. 989, 



LtyX. PBOC. — BOTANV, VOL. IX. 



F 



