THE BEHAVIOR OF INFUSORIA; PARAMECIUM 91 



serve for defence seems questionable. Certainly the infusorian Didi- 

 nium (Fig. 113), which is the chief enemy of Paramecium, is not hindered 

 in the least from seizing and devouring the animal by the discharge of 

 trichocysts. It is possible that the discharge is really an expression of 

 injury, a purely secondary, even pathological, phenomenon, like the 

 formation of vesicles on the surface of an injured specimen. 



LITERATURE V 



A. Reaction of Paramecium to electricity : VERWORN, 1889 a ; LUDLOFF, 1895 ; 



BlRUKOFF, 1899, 1904; ROESLE, 1902; PUTTER, 1900; SXATKEWITSCH, 1903, 



1903 a, 1904; JENNINGS, 1904 h; BANCROFT, 1905; COEHN AND BARRATT, 1905. 



B. Discharge of trichocysts as a reaction : M ASSART, 1901 a. 



