n8 A YORKSHIRE NATURALIST 



of the wall of the parent Volvox, to which it had 

 thus far firmly adhered, and floated free in the 

 interior of the older organism, along with four or 

 five others similarly developed. Finally the parent 

 structure broke up, liberating the young forms, each 

 of which then became the parent of a succeeding 

 generation. 



This series of observations not only demonstrated 

 that Volvox was a plant, but it has since been made 

 the type of a cryptogamic group, now recognised as 

 the Volvocineae. But though I thus succeeded in 

 laying the foundation of a scientific treatment of 

 this lovely object in 1851-52, more had yet to 

 be done before we obtained a fuller knowledge of 

 its remarkable history. Stein and my old friend 

 Professor Cohn, of Breslau, brought to light many 

 important facts connected with its sexuality; yet 

 we are still far from knowing all about it. It is 

 evident that Volvox is subject to some change 

 equivalent to an alternation of generations, apparently 

 dependent upon changes in the seasons, as well as 

 upon other changes in its surroundings. The 

 boundaries of the species are far from deter- 

 mined, notwithstanding what Klein has recently 

 done in that direction. These objects still attract 

 by their fairy-like aspect, and they have now 

 become more interesting because of the remarkable 

 morphological and physiological phenomena which 

 what we know of their life -history has already re- 

 vealed. 



