320 



ASYMMETRY IN CERTAIN LOWER ORGANISMS, 



most of the ciliate infusoria, as is well known; this will be appreciated by- 

 examining the plates in BiitschU's ('87-'89) great work on this group. From many 

 of the figures it will be evident further that the body has really a tendency 

 to a spiral structure, — and the spiral form is really present in many species 

 where it is not evident from the figures. The spiral feature may appear in the 



Fig. C. — Figures of Ciliate Infusoria, after Butschli, showing the spiral form. 

 1, Condylostoma patens 0. F. M.; 2, Anoplophrya branchiarum Stein; 3, Uronema torta Maupas; 4, Col- 

 poda cucullus O. F. M., ventral view; 5, the same, right side; 6, Caenomorpha medusula Perty; 7, Spirostomum 

 ambiguum Ehrbg. (dividing). 



general form, the position and form of the peristome, and in the arrangement of cilia 

 on the body. In Figure C are shown a number of cases in which the spiral character 

 is particularly noticeable. 



In all cases studied by the author the unsymmetrical form of the ciliate 

 has been correlated with a spiral path, the body of the organism maintaining a 

 constant relation to the axis of the spiral. 



In the Flagellata asymmetry is likewise widespread, and in many of these 

 organisms the spiral form is especially striking. This is the case, for example, 

 in the species shown in Figure D. In many other species the form is really 

 partly spiral, though this does not always appear in figures. These unsymmetrical 



