THE GREEN CELLS OF CONVOLUTA ROSCOPFENSIS. 171 



to be a clilamydonioiias. Schewiakoff (1891) successfully 

 fed colourless Frontonia ou macerated green specimens, and 

 states briefly that multiplication of the green cells within the 

 host occurred. Dantec obtained a like result with Para- 

 mecium. 



Brandt (1883), after depriving sea anemones of their 

 yellow cells by long confinement in the dark, caused the 

 reappearance of these cells by placing the animal in fresh 

 sea-water in the light. But from experiments made by 

 ourselves, we venture to express some doubt as to whether 

 the apparently colourless animal had lost absolutely all its 

 yellow cells. 



Haberlandt (1891), whose admirable work on Convoluta 

 roscoffensis is referred to in the text of this paper, was 

 unsuccessful in his attempts to cultivate the green cells of 

 this animal. Pending more exact information it seems to us 

 that Lankester (1882 and 1890) has done valuable service by 

 his championship of the opposed view, that of the intrinsic 

 nature of the corpuscles under discussion. For his view com- 

 pels those who hold the ''algal" theory to investigate each 

 case separately and to vindicate their view by the synthesis 

 of the green animal. 



When this has been done in such cases as those in which 

 cell-wall and nucleus are present in the corpuscles, there Avill 

 remain others — e. g. Hydra and Spongilla, whose green 

 cells are devoid of definite nuclei, and after these, such 

 puzzling instances as Vorticella campanula (Engel- 

 mann, 1883), with its diffuse chlorophyll, as well as 

 Pelomyxa viridis (Bourne, 1891), the green corpuscles of 

 which seem difficult of explanation except on Lankester's 

 hypothesis. 



Influenced by the forementioned considerations, we have 

 investigated the origin of the green cells of Convoluta 

 roscoffensis. The results of this investigation are set forth 

 in Sections II — V. 



The experimental work recorded in this paper has been 

 carried on in the laboratory at Tregastel, C6tes-du-Nord, 



