Feb. 1902.] BOTANICAL SOCIETY OF EDINBUEGH 185 



consequence of the lower pitch of vitality and greater 

 individuality of plant protoplasts. As the wheel continues, 

 in virtue of its inertia of motion, to rotate, it may be for a 

 considerable time after the driving gear is slipped, so many 

 plant organs and cell organoids continue to function for a 

 time when isolated. This is a manifestation of their kata- 

 bolic inertia. Isolated chloroplasts, for example, assimilate 

 for five hours (Ewart, "Jour. Linn. Soc," xxxi. p. 420); 

 isolated endosperm of Ricimts lives and carries on meta- 

 bolic change for six months (Van Tieghem, " Ann. d. Sc. 

 Nat.," 187G, Ser. vi., T. iv., p. 183), a fact which may be 

 of interest in connection with xenia and double fertilisa- 

 tion. Isolated scutellar epithelium secretes enzymes and 

 corrodes starch grains (Brown and Morris, "Jour. Chem. 

 Soc. Trans.," vol. Ivii., 1890, p. 49-4). Isolated fragments 

 of swarmspores move, and of cytoplasm stream, while 

 Demoor found that nuclei continued their mitosis after 

 the cytoplasm was killed by CO2 or chloroform (Pfeffer, 

 "Physiology," p. 52). Again, isolated leaves of Drosera 

 continue active, translocation takes place in heads of 

 cereals (Pfeti'er, loc. cit. p. 585), and ripening in fruits 

 after separation from the parent plant ; and oak galls 

 continue their internal metabolic changes when removed 

 from the tree (MacDougal, "Physiology," p. 64). 



In the consideration of rhythm or periodicity we again 

 meet with interesting examples of inertia. Thus, in virtue 

 of their functional inertia, plants continue to exhibit daily 

 periodicity of growth for periods varying from two days to 

 as many weeks in continuous darkness. Some trees, like 

 the oak and beech of temperate regions, which exhibit 

 a seasonal periodicity, retain that periodicity when removed 

 to countries where the vegetation is evergreen ; they do so 

 in consequence of their great amount of inertia. Other 

 temperate trees, again, possessed of a' smaller amount of 

 inertia, lose their periodicity after a time and become ever- 

 green, e.g. the plum and the peach. On account of 

 possessing relatively little inertia, again, some plants will 

 " force " and Hower out of season, others with more inertia 

 are refractory. By cold storage — artificially keeping the 

 plant in a condition of anabolic inertia — the refractoriness 

 of the latter may be in some measure overcome. 



TKAXS. BOT. SOC. EDIX. VOL. XXII. N 



