H. MUNRO FOX 



505 



along the four sides with vaseline so that the suspension was every- 

 where shut off from the air (Fig. 14). For comparison a second 

 preparation was made which was vaselined along two of its four 

 open edges. This was done to eliminate any possible injurious effect 

 of the vaseline on the Bodo, which would now be the same on both 

 slides. 24 hours afterwards almost all the flagellates in the sealed 

 preparation were motionless, just a few swimming feebly or vibrating. 

 In the open preparation there were normal bands of flagellates at a 



n 



Fig. 14. Experiment to test the effect of the absence of oxygen on flagellates. 

 Edges of the cover-glass were sealed with vaseline, a, vaseline. 



,^y■*•=:^'>■■^'•■<*•'•,^.. 



a 



Fig. 15. Experiment to test the effect of the absence of oxygen on flagellates. 

 Two sides of the cover-glass were sealed with vaseline. Distribution of flagellates 

 after 24 hours, a, vaseline. 



certain distance inside the free edges (Fig. 15). 48 hours from the 

 start of the experiment the Bodo in the sealed slide were in the same 

 motionless condition as on the previous day, while those in the open 

 preparation were in full activity, the bands having retracted in the 

 usual manner to form a ring near the center. A small aperture was 

 now made in the vaseline wall surrounding the sealed preparation 

 so that the air came into contact with the water of the suspension 

 at this point. Instantaneously all the Bodo in the neighborhood of 



