Feb. 1902.] BOTANICAL SOCIETY OF EDINBURGH. 187 



acclimatised, but others not at all ; the former have relatively 

 little inertia as compared with the latter. 



Protoplasm can be gradually acclimatised to an atmo- 

 sphere of 1 part oxygen to 4 of COo, which, when 

 directly applied, inhibits all movement (Lopriore ; Mac- 

 Dougal, "Physiology," p. 57). 



Consideration of these cases of single stimuli makes it 

 clear that plant protoplasm has not always the same 

 amount of functional inertia, and further, that the time 

 value of the inertia varies very widely in different organs 

 in respect of the same stimulus. Thus it ranges from 

 periods of time measured by seconds to hours or days, and 

 it has been indicated that it is possible to artificially 

 lengthen the period. There still remain to be considered 

 those cases where the amount of inertia is so considerable 

 that more than one stimulus is necessary to elicit a 

 manifestation of irritability, and where, furthermore, the 

 inertia assumes the character of a physiological insus- 

 ceptibility, inasmuch as the reaction is only called forth 

 by a particular combination of stimuli. 



Pierce (" Proc. Calif. Acad. Sc," Ser. III. ii., 1901, p. 83, 

 also "Bot. Central. Bd.," Ixxix., 1902, p. 36) describes a case 

 of redwood stumps producing white sucker.s. No chloro- 

 phyll was developed, according to Pierce, because of the 

 low inhibitory temperature; the shoots were parasitic on the 

 underground parts of the tree. The temperature rose, and 

 the inhibitory was replaced by an inducing stimulus, but 

 yet no chlorophyll was developed. From our point of view 

 the plants were thus manifesting great functional inertia 

 of anabolism. Only when a second stimulus came into 

 action (a change in the food conditions) was there a response 

 in the production of green leaves. The anabolic inertia 

 was here so great that tico stimuli of a tonic character, 

 conditions of temperature and food supply, were required 

 to elicit the manifestation of irritability. 



A more extreme case still is furnished in the winter 

 buds of Ri/drocharis. Terras found (" Trans. Bot. Soc. 

 Edin.," xxi., 1900, p. 318) that if covered up theSe buds 

 could be kept in the dormant condition, that is in a condi- 

 tion of anabolic inertia, for at least tv:o years. To induce 

 germination, heat, light, and oxygen were necessary. So 



