86 



HYFOCOTYLS, EPICOTYLS, ETC., CHAP. II. 



stem of the parasitic and leafless Monotropa hypopitys. 

 With Hetttiborus niyer, the ilower-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 Epimedlum 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- 

 Una), 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 that 

 there is any reason to suppose 

 that the secretion is a special 

 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 and wry dry, but it was 

 dark coloured and damp, even in 

 parts quite wet. for a distance of 

 al least six inches all round each 

 flower-stem. The water is secreted 

 by glands (described by Colin, 

 'Bericlit. Bot. Sect, der Schle- 

 sischen Gesell.,' 1876, p. 113) 

 which line the longitudinal 

 channels running through each 

 scale-like leaf. A large plant was 

 dug up, washed so as to remove 

 the earth, left for some time to 

 drain, and then placed in the 

 evening on a dry glass-plate, 

 covered with a bell-glass, and by 

 next morning it lal secreted a 

 large pool of water. The pLte 

 was wiped dry, and in the course 

 of the succeeding 7 or 8 hours 



another little pool was secreted, 

 and after 16 additional hours 

 several large drops. A smaller 

 plant was washed and placed in a 

 large jar, which was left inclined 

 for au hour, by which time no 

 more water drained off. The jar 

 was then placed upright and 

 closed : after 23 hours twodmchms 

 of water were collected from the 

 bottom, and a little more after 2o 

 additional hours. The flower- 

 stems were now cut off, fur they 

 do not secrete, and the subter- 

 ranean part of the plant was found 

 to weigh 106-8 grams (1611 

 grains), and the water seer* ted 

 during the 48 . hours weighed 

 1T9 grams (183 grains), that is, 

 one-ninth of the whole weight of 

 the plant, excluding the flmver- 

 stems. \Ve should rememlx 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 para- 

 sitic. 



