60 THE PHYSIOLOGY OF MUSCLE AND NERVE. 



The ciliary movement is affected by variations in temperature, and 

 if the temperature passes beyond an optimum point the cilia fall 

 into a condition resembling heat rigor in the muscle. Their move- 

 ments are affected also by the reaction of the medium, being at 

 first accelerated and then slowed or destroyed by a slight degree 

 of acidity and favored by a very slight degree of alkalinity.* 



* References for physiology of ciliary movement: Verworn, "General 

 Physiology," English translation by Lee; Putter, " Ergebnisse der Physiol- 

 ogic," 1902, vol. ii, part n; Engelmann, article, "Gils vibratils," in Richet's 

 " Dictionnaire de Physiologic," vol. iii, 1898. 



