46 CIKOUMNUTATION OF SEEDLINGS. CiiAr. 1 



on the following day with nearly the same result; and there 

 oaii be no doubt about the circummitation of the hypocotyL 



Fig. 33. 



S^rimnia Sinensis: eonjtitnt uircumnutatron of hypocotyl and cotytetfoi^ 

 traced on vertical glass, from 8.40 a.m. to 10.45 P.M. MovemeBts ol 

 bead magiaitied about 2G times. 



Cyelamen Persicum (Primulacece). — This plant is generally sup- 

 posed to produce only a single cotyledon, but Dr. H. Gressner * 

 has shown that a second one is developed after a long interval 

 of time. The hypocotyl is converted into a globular C(xcm, even 

 before the iirst cotyledon has broken through the gvo-und with its 

 blade closely enfolded and with its petiole in the fe>rm of an arch, 

 like the arched hypocotyl or epicotyl of any ordinary dicotyle- 

 donous plant. A glass filament was affixed to a cotyledon, '55 

 of an inch in height, the petiole of which had straightened itself 

 and stood nearly vertical, but with the Wade not as yet fully 

 expanded. Its movements were traced during 24^ h. on a 



horizontal glass, magnified 50 

 f 'g- ■"■*• times ; aad in this interval it 



described two irregular small 

 circles; it therefore circumnu- 

 tates, though on aa extremely 

 small scale. 



Sfapeiia sarpediin (Ascle- 

 piadesa). — This plant, whea 

 mature, resembles a cactus. 

 The flattened hypocotyl is 

 fleshy, enlarged in the uppei 

 part, and bears two rudimen- 

 tary cotyledons. It breaks 

 through the ground in an arched form, with the rudimentary 

 ootyledons closed or in contact. A filament was affixed almosi 



Strjpdia sarpcdon : eirctimnutatron 

 of hypocotyl, illuminated from 

 above, traced on horizontal glass, 

 from 6.45 a.m. June 26th to 8.45 

 A.isi. 28th. Temp. 23°-24° C. 

 Movem'^nt of bead magnified 21 

 times 



• ' Bot. Zeitung,' 1874, p. 837. 



