LITERATURE 67 



lireetly dependent upon it, and certain excretory processes are 

 imulated by it. The motion of protoplasm is likewise de- 

 jndent upon water, which determines the unstable condition 

 that substance. Desiccation, therefore, produces a rigor, 

 ind this may continue, in the absence of water, for months, and 

 even years, the organism being, meanwhile, ready to awake 

 to activity upon the return of moisture. The degree of desic- 

 cation which organisms can resist varies. In the case of the 

 higher organisms, it is slight ; in the case of bodies especially 

 adapted to resist dryness (spores, seeds, statoblasts), there is, 

 perhaps, no practicably attainable limit to the dryness which 

 their protoplasm may undergo without loss of power of revivifi- 

 cation. The condition of desiccation-rigor is not known to be 

 one of death which is replaced by life upon return of moisture. 

 It is probably rather a condition of minimum metabolism. 

 The great resistance capacity exhibited by certain organisms is 

 correlated with their liability to desiccation in their natural 

 surroundings. Finally, Myxomycetes (and probably other or- 

 ganisms) respond to inequalities in the amount of moisture 

 in their environment, moving either towards or from greater 

 moisture. We recognize thus that the activities of protoplasm 

 are to a large extent dependent upon the existence of water in 

 it ; and that protoplasm reveals itself as sensitive to differences 

 in the amount of moisture, responding by secretions, by the 

 assumption of a quiescent condition, and by locomotion with 

 reference to water. ' 



LITERATURE 



BLAINVILLE, H. DE '26. Sur quelques petits Animaux qui, apres avoir 

 perdu le mouvement par la dessication, le reprennent comme aupara- 

 vant quand on vient a les mettre dans 1'eau. Ann. des Sci. Nat. IX, 

 104-110. 



BEZOLD, A. VON '57. Untersuchungen liber die Vertheilung von Wasser. 

 organischer Materie und anorganischen Verbindungen im Thierreiche, 

 Zeitsch. f. wiss. Zool. VIII, 487-524. 26 Feb. 1857. 



Bos, R. '88. Untersuchung iiber Tylenchus devastatrix, KUHN. Biol. Cen- 

 tralb. VII, 646-659. 1 Jan. 1888. 



BROCA, P. '61. Rapport sur la question soumise a la Societe de Biologie 

 par MM. POUCHET, PENNETIER, TIXEL et DOYERE au sujet de la revi- 

 viscence des animaux desseches, lu par M. PAUL BROCA au nom d'une 



