686 



PROTOZOOLOGY 



Growth and nuclear division (Hegner and Wu, 1921); cytology (ten 

 Kate, 1927). 



0. hylaxena Metcalf (Fig. 294, a). In Hyla versicolor; largerin divid- 

 ual about 420m long, 125m wide, 28/z thick. Several subspecies 

 (Metcalf). 



0. obtrigonoidea M. (Fig. 294, b-d). 400-840/x long, 175-180/x wide, 

 20-25ju thick; in various species of frogs and toads (Rana, Hyla, 

 Bufo, Gastrophryne, etc.), North America. Numerous subspecies 

 (Metcalf). 



Fig. 294. a-i, 1, Metcalf; j, k, Leger and Duboscq. a, two individuals of 

 Opalina hylaxena, X78; b-d, three individuals of 0. obtrigonoidea, X78 

 (b, from Bufo fowleri; c, from Rana pipiens; d, from R. palustris) ; e, four 

 individuals of Cepedea cantabrigensis, X 78 ; f-i, stages in sexual reproduc- 

 tion in Protoopalina intestinalis; j, k, P. saturnalis, X500; 1, P. mitotica, 

 X240. 



