186 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lxvi. 



Plants wliicli have a daily periodicity of movement, 

 such as sensitive plants, daisy, and so forth, exhibit post- 

 stimulant periodic movements in continuous darkness. 

 This is one expression of their functional inertia. 



Evidence on similar lines can be adduced from the 

 interesting experiments of Darwin and Pertz (" Annals of 

 Botany," vol. vi. p. 425), and others, on induced rhythm 

 in different organs. 



Polarity, according to Detmer ("Physiology," p. 507), 

 may be regarded as an " after effect phenomenon induced 

 by gravitation and stretching beyond the life of the 

 individual, as a phenomenon of inherent or stable induction, 

 and therefore an inheritable disposition." For the more 

 or less indelible impression of this character by summation 

 of effects, the property of functional inertia would be 

 a necessary preliminary. On account of their greater 

 functional inertia, polarity is more indelibly stamped on 

 some plants than on others, and in the latter, in con- 

 sequence of their smaller degree of inertia, it is possible to 

 alter the polarity by the influence of external conditions. 

 It would seem that in the acquirement of characters 

 generally by living matter, i.e. in the " education " of 

 protoplasm, functional inertia is a factor of great import- 

 ance. 



The time taken for summation of effects, for the educa- 

 tion or acquirement of characters, will depend on the 

 amount of inertia displayed by the protoplasm in relation 

 to the particular stimulus. Time is an element of the 

 process, and this represents the time value of the func- 

 tional inertia. The following cases might be cited as 

 bearing on this point in particular, but additional examples 

 will present themselves to every botanist. 



Stahl ("Bot. Zeit.," 1884), by gradually adding glucose 

 to water in which JEthalium plasmodium was growing, 

 succeeded in growing it ultimately in a 2 per cent, solu- 

 tion, which would, under ordinary circumstances, have 

 killed it. 



It is a well-known fact that sporeless and other varieties 

 of bacteria may be obtained by continued cultivation in 

 particular nutrient solutions under special conditions. 



Again, it has been pointed out that some plants can be 



