^'^^- 3] Bovarcl. — Condylostoma patens. 357 



11. SWIMMING. 



Far less than one-half the time is given over to swimming. 

 Condylostoma shares with Bursaria the disposition to spend most 

 of its time on the bottom of the aquarium. This seems to be 

 characteristic of many of the larger ciliates, Spirostomum, Lox- 

 odes, Lionotus, Bursaria, of which many are found in the waters 

 with Condylostoma. They all show the tendency to swim in a 

 spiral when stimulated sufficiently to cause them to leave the 

 substratum. 



The mechanism and sigijificance of the spiral swimming 

 amongst swarm spores, flagellates, ciliates, and rotifiers has been 

 thoroughly gone over in Jennings' work on Animal Behavior 

 ('99 and :04). 



Fig. 10. — The various phases exhibited by an animal during swimming as 

 seen from above. 



As the animal moves through the water it will be noticed that 

 it is revolving on its long axis, the body swerving and not 

 pursuing a straight course. Closer analysis will show that this 

 movement is in a spiral which varies considerably with ditferent 

 individuals. If we should see the animal swimming toAvards us, 

 the anterior end would seem to describe a circle turning in the 

 same direction as the hands of a clock. It would be also noticed 

 that this end was always orientated in the same way, the con- 

 cave side of the adoral zone always facing the inner side of the 

 circle. Applying this now to the movement, we have the animals 

 swimming in a spiral with the buccal groove always facing the 

 inside of the spiral, which is the case in other ciliates, Loxodes 

 and Paramaccium for example. See Jennings ( :04). 



The rotation of the animal while following this spiral is the 

 same as for Paramaecium, that is, while the animal is moving 

 away from the observer, the upper surface is constantly moving 

 to its left. Fig. 10 illustrates the different phases that the animal 



