42 



BEHAVIOR OF THE LOWER ORGANISMS 



body is slender but blunt, the posterior part thicker, but more pointed. 

 Thus the two ends differ, as in some bacteria, and there is a further 



Fig. 31. — Examples of ciliate infusoria, a, Spirostomum ambiguum Ehr., after Stein. 

 b, Stentor rceselii Elir., after Stein, c. Varticella nehulifera O. F. M., after Biitschli. d, Col- 

 pidium colpoda Ehr., after SchewialiofE, from Butsciili. e, LoxophyUum meleagris O. F. M., 

 after Biitschli. /, Stylonychia mytilus Ehr., after Engelmann. 



differentiation of the lateral surfaces. One side, the oral surface, bears 

 a broad, oblique groove, known as the oral groove, or peristome, ex- 



