184 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. Lxvi. 



prevented, and the anabolic period may be prolonged for 

 eight days. A fever reaction is induced in massive tissues, 

 as potato tubers, by incised wounds after a reaction period 

 of two hours or so (Richards, " Annals of Botany," x. p. 531, 

 and xi. p. 29). According to Townsend ("Annals of Botany," 

 xi. p. 515), amputation of a small piece of the root apex is 

 followed after a latent period of twenty-four hours by a 

 retardation of growth in the root and an acceleration of 

 growth in the stem. The long latent period of five or six 

 days elapses between the application of the traumatic 

 stimulus and the manifestation of irritability — a peculiar 

 healing reaction — in isolated leaves of Prunas lauro-cerasus 

 (Blackman and Matthaei, "Annals of Botany," xv. p. 533). 



Oxygen. — Absence of free oxygen inhibits streaming in 

 Chara, but only after a considerable period of katabolic 

 inertia (Ewart, "Jour. Lin. Soc," xxxi. p. 421 ; also J^armer, 

 " Annals of Botany," x. p. 286), while obligate aerobia con- 

 tinue to move from five to sixty minutes in the absence of 

 free oxygen (Pfeffer, "Physiology," p. 569). 



The list of examples might be indefinitely extended. 

 Interesting cases of physiological insusceptibility are sup- 

 plied in Arber's researches on the CO2 assimilation of 

 halophytes (" Annals of Botany," xv. pp. 39 and 669), in the 

 thermo-secretory phenomena of nectaries (Pfeffer, " Physio- 

 logy," p. 286), in Pfeffer's " Chemotactic Application of the 

 Weber-Fechner Law," in the vital phenomena of parasites, 

 fungal and other. On the other hand, E wart's researches 

 on assimilatory inhibition ("Jour. Lin. Soc," xxxi. pp. 364, 

 554; " Annals of Botany," xi. p. 439) are a mine of examples 

 of both phases of functional inertia. In many cases the 

 biological significance of the time-value of the functional 

 inertia is of the highest importance. Thus (Ewart, " Annals 

 of Botany," xii. p. 378) mosses have much katabolic inertia 

 to desiccation, and relatively little anabolic inertia to mois- 

 ture ; they continue to assimilate for two to five days during 

 desiccation, and when desiccated they resume operations on 

 moisture being supplied in the short period of a few hours. 

 The same is true of other members of Alpine floras, and 

 the importance of it is manifest. 



Passing on to consider the functional inertia of excised 

 and isolated organs, we again find no lack of examples, in 



