FUNCTIONAL INERTIA AS LATENT PERIODS, &c. 47 



parallel the resting seed in its condition of vie 

 latente or Scheintod, we find them, perhaps, in 

 the desiccated state of tardigrada and rotifera, and 

 very likely it will be found that these organisms, 

 when thoroughly desiccated, can withstand the 

 same extraordinary tests as the dry seed." 



The winter sleep of animals, the winter rest of 

 plant-organs, roots, buds, &c., is due to a phasic 

 increase of functional inertia : the rhythm of 

 hibernation, for instance, cannot be wholly accounted 

 for by postulating affectability alone. That hiber- 

 nation does not depend on the affectability of at 

 least the cerebral protoplasm, is shown by the fact 

 tha': decerebrate frogs if kept alive long enough will 

 proceed in due time to hibernate. Dubois, in writing 

 on hibernation, distinctly indicates that he cannot 

 regard it as due to the environment ; the animals, 

 he says, are " tomb^s dans un dat d'inertie complete." 



Paget * cites the interesting case of migratory 

 birds. " Among migratory birds also, it has been 

 observed that when they are kept in confinement, 

 and removed from all the circumstances that might 

 be supposed to induce or necessitate their journeys, 

 they yet become restless at the return of the season 

 for their migration." 



The organic rhythm of menstruation in the human 

 female is an example of a typically periodic function, 

 occurring as it does every twenty-eight days through- 

 out reproductive life. When one considers it in the 

 healthy woman, and remembers how the environ- 



* Paget, loc. cit. p. 124. 



