XII 







I* 

 



In the centre ten dead Paramecia, killed by healing. The dots indicate the turn- 

 ing points of the living Paramecia, exactly marked by means of the camera clara. 



the same time, always by means of the camera, asuf- 

 iicient number of the points where the animalcula turn 

 about; the above figure has been made in this way. 

 b. The mode of reaction is not the same for all the 

 different species of infusoria. It depends on the nor- 

 mal movements characteristic of each species. There 

 are some who draw back suddenly with a move- 

 ment of terror (,,Schreckbewegung"), as Engelmann 

 calls it; others retire slowly in a curve, others again 

 stop a moment before moving back. A certain 

 number react in a particular way at a somewhat 

 greater distance from the dead bodies, executing a 

 series of rapid rotations round their axes like the 



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