86 



HYPOCOTYLS. EPICOTYLS, ETO, Chap. 11. 



Stem of the parasitic and leafless Monotropa hypopifi/s. 

 With Helleborus niger, the flower-stems, which rise up 

 independently of the leaves, likewise break through 

 the ground as arches. This is also the case with the 

 greatly elongated flower-stems, as well as with the 

 petioles of Epimedium pinnatum. So it is with the 

 petioles of Ranunculus fiearia, when they have to break 

 through the ground, but when they arise from the 

 summit of the bulb above ground, they are from the 

 first quite straight ; and this is a fact which deserves 

 notice. The rachis of the bracken fern (Pteris aqui- 

 lina), and of some, probably many, other ferns, like- 

 wise rises above ground under the form of an arch. 

 No doubt, other analogous instances could be found by 

 careful search. In all ordinary cases of bulbs, rhizomes, 



ranean scale-like -leaves : not tliat 

 thi re is any reason ii snppose 

 that the secretion id a spceial 

 adaptation for this purpose : it 

 probably follows from the great 

 quantity of sap absorbed in the 

 early spring by the parasitic roots. 

 After a long period without any 

 rain, the earth had become light- 

 coloured anil vtry dry, but it was 

 dark coloured and damp, even in 

 parts quite wi t, for a distance of 

 a1 least six inches all round each 

 flower-stem. The water is secreted 

 by glands (ilesoiibed by Cohn, 

 'Bericl.t. Bot. Sect, der Sclile- 

 tisolicn Gesell.,' 1876, p. 113) 

 wliich line the longitudinal 

 cliannels running through edch 

 Bcale-like leaf. A large plant was 

 dug up, washed so as to remove 

 tlie earth, left for some lime to 

 drain, and then placed in the 

 evening on a dry glnss-plate, 

 covered with a bell-glnss, and by 

 next morning it 1 a 1 secreted a 

 large pool of water. The pli te 

 was wiped dry, nnd in the course 

 of the succecdhig 7 or 8 liours 



another little pool was secreted, 

 and after 16 additional hours 

 several large drops. A i-malli r 

 plant was Wiished and placed in a 

 large jar, which was left inclined 

 for an hour, by whicii time no 

 more water drained off. Tne jar 

 was then placed upriglit and 

 closed : after 23 hours twodrachms 

 of water were collected from the 

 bottom, and a little more after 25 

 additional hours. The flower- 

 stems were now cut off, for they 

 do not secrete, and the subter- 

 ranean part of tlie plant was found 

 to weigh 106-8 grams (1611 

 grains), and the water secreted 

 during the 48 . hours weighed 

 11-9 grams (1S3 grains). — that is, 

 oiie-nintli of the whole weight of 

 the plant, excluding the flower- 

 stems. We should rememb; r that 

 plants in a state of nature would 

 probably secrete in 48 hours much 

 more than the above large amount, 

 for their roots would continue all 

 the time absorbing sap from the 

 plant on which they were par» 

 sitio. 



