108 F. BATES ON SEXUALITY IN THE ZYGNEMACE^. 



form of conjugation, as it exists typically in the genus Mesocarpus, 

 exhibits a more rudimentary differentiation of the sexual elements 

 than exists in the Zygnemece. This seems to me most astounding, 

 for he cannot be ignorant of the fact that De Bary, Pringsheim, 

 Wittrock, and others who have closely and patiently observed 

 all the phenomena of conjugation in these forms, have been led to 

 separate Mesocarpus and the allied genera from the Zygnemece, and 

 to elevate them into a distinct sub-family — the Mesocarpece, owing 

 to the more advanced type of sexual development they exhibit. 



