STIMULI AND THEIR ACTIONS 



387 



undisturbed, and tlieu- protoplasm flows slowly but constantlj^ 

 without exception in a centripetal direction. But, if the shaking 

 be more intense, they assume a varicose appearance, their centri- 

 petallj' streaming protoplasm collecting into many small spindles 

 and globules, of which the smaller flow into the adjacent larger 

 ones, while the larger ones constantl}' approach the central 

 protoplasmic bod}'; upon long-continued action all protoplasm 

 flows into the cell-bodj^^ This curious formation of droplets 

 upon pseudopodia is a peculiarity of strongly and continually 

 stimulated protoplasm which is general in Rhizopoda that are 

 provided with filose pseudopodia ; it is only a special case of the 

 general law that strong stimuli cause naked protoplasmic masses 



Fui. ISO.— Orbllolites. A part of the surface of the shell, with extended, thread-like pseudopodia. 

 A, Unstimulated ; .S, after vigorous shaking. 



to assume the spherical form. The same tendency toward the 

 formation of globules, which all stimulated protoplasm as a whole 

 shows, is also noticeable in its individual parts.- 



Ciliary motion is increased gi-eatly by rhj'thmically inter- 

 mittent shocks, so that Infusoria stimulated in this waj' rush 

 madly through the water for a considerable time after the 

 stimulation has ceased. A real tetanus, however, in which the 

 cilia remain bent in the position of contraction, appears not to 

 occur, at least thus far such has not been observed. The 

 rhythmic motion of the cilia continues, and is changed in its 

 rate and amplitude only. 



1 (.';'. Verworn ("92,1). 

 C/. herewith the phenomena of necrobiosis, p. 329, Fig. 142. 



C C 2 



