1512 Journal of Applied Microscopy 



the anode or the kathode as the case may be. There is no ciliary reversal on 

 the kathode half of the body, as has been described by several observers in the 

 case of the free living infusoria. The author lays stress on the parallelism in 

 the forms he has studied between the effect of chemical and electrical stimuli on 

 the ciliary action. 



Experiments were made with media of different electrical conductivities. It 

 was found that in both hyper- and hypotonic solutions Opalina and Nyctotherus 

 show a tendency to pass to the kathode pole, although the reaction varies some- 

 what. Experiments with Paramecium and Colpidium in salt solutions showed 

 that, under these conditions, both of these ordinarily kathodic forms went to the 

 anode when the current was passed. It is maintained that probably nearly all 

 the ordinarily described electrotactic reactions are conditioned by the conduc- 

 tivity of the solution in which they are tested, and that they may disappear or 

 be replaced by very different responses under different conditions. 



The author considers the general phenomenon of electrotaxis to be the result 

 of two factors ; one, a rheotactic reaction to the current of fluid produced by the 

 kataphoric action of the electric current, and the other a chemotactic reaction to 

 the acid continually set free at the anodic, and the alkali at the kathodic end of 

 the body. Whatever may be one's opinion as to the adequacy of this theory, the 

 work as a whole is an extremely important and well developed contribution to 

 the discussion of the phenomenon of electrotaxis. r. p. 



Jennings, H. S. On the Significance of the It has long been known that a great 

 Spiral Swimming of Organisms. Amer. , . , 



Nat. 35: 369-378, 1901. i^^^Y lower organisms (e.g., swarm- 



spores, flagellate and ciliate infusoria, 

 rotifers, and others) swim in a spiral path. It is the purpose of the present 

 paper to explain the biological significance of this form of progression. It is 

 very clearly shown by Dr. Jennings that the purpose and result of this movement 

 in a spiral is to keep the animal on a straight course. Most of the infusoria are 

 unsymmetrical, and as they start to move forward they are swerved from a 

 straight course as a result of this asymmetry. This swerving is always towards 

 the same, structurally defined, side of the body. If, however, as is in fact the 

 case, the organism rotates on its long axis as it advances, it is at once apparent 

 that any tendency to swerve to one side from the straight course will compensate 

 itself, thus leaving the forward component of the motion the only effective one, 

 and making the path a spiral with a straight axis. This method of swimming 

 is closely related to the method of reaction to stimuli of these organisms, since 

 the side of the body towards which the infusorian turns in the " motor reflex " 

 is always directed away from the axis of the spiral. Not only asymmetrical 

 organisms use this method of keeping on a straight course, but many bilaterally 

 symmetrical rotifers also swim in a spiral path. These rotifers have a marked 

 tendency, when moving freely in the water, to swerve towards the dorsal side. 

 This tendency is the one compensated for by the spiral swimming in this case. 

 Correlations between the method of movement and the form of the body in other 

 cases are discussed. r. p. 



