86 



HYPOCOTYLS. EPICOTYLS, ETC., Cuap. II. 



stem of the parasitic and leafless Monotropa hypopitijs. 

 With Hellehorus 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 Ranimculus ficaria, 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 grouiid 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 that 

 tliire is any leason to suppose 

 that the secretion is a special 

 adaptation for Ihis purpose : it 

 probably follows from the ^reat 

 quantity of sap absorl)ed in the 

 early sprin;;; by the parabitie roots^ 

 After a long period without any 

 rain, the eartli had become liglit- 

 coloured and very dry, but it nas 

 dark coloured and damp, even in 

 fiarts quite w(-t. for a distance of 

 al least six inches all round each 

 Hower-stem. The water is secreted 

 by glands (described by Cohn, 

 ' Berioht. Bot. Sect, der Solile- 

 H3c:;en Gesell.,' 1876, p. H3) 

 wl.icli line the longitudinal 

 cliaunels lunniiig through e.icli 

 scale-like leaf. A large plant was 

 dug up, washed so as to remove 

 the earth, left (or some time to 

 drain, and then plac(;d iu tl'.e 

 evening on a dry glass-plate, 

 covered with a bell-glass, and by 

 next morning it liad secreted a 

 large pool of water. The pl;:te 

 was wiped dry, and in the course 

 of tl)e succeeding 7 or 8 houi-s 



another little pool was secreted, 

 and after 16 additional hours 

 several large drops. A smaller 

 plant was washed and placed in a 

 lai-ge jar, which was left inclined 

 for au hour, by whicli time no 

 uiore wiitL-r drained off. The jar 

 was then placed upright and 

 closed : after 23 hours twodnichms 

 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 the plant was found 

 to weigh 1U6-8 grams (1611 

 grains), and the water seoifted 

 during the 48. hours weigheil 

 11 '9 grams (1^3 grains). — that is, 

 one-ninth of the whole weight of 

 the plant, excluding tlie flower- 

 stems. We should remerab;r that 

 plants in a state of nature would 

 probably tecrete in 48 hours much 

 more than tlie above largo amount, 

 for their roots would continue all 

 the tiine ahsorbing sap from the 

 plant on which they were para- 

 sitic. 



