in] GREEN CELLS OF CONVOLUTA 81 



driven to accept the latter alternative, and to conceive 

 of C. roscoffensis as an animal which lives like a plant, 

 in other words, as a plant-animal. This conclusion 

 forces us to direct our attention to the plant-like 

 green cells which form such a prominent tissue in 

 the body of C. roscoifensis. 



From the general considerations which we have 

 just advanced, it would appear to follow that the green 

 cells possess the power, common to those of green 

 plants, of manufacturing carbohydrate food-materials 

 from the simple, inorganic, soluble substances, water 

 and carbon-dioxide, andpossibly also of manufacturing 

 complex nitrogen-containing food-substances, such as 

 proteins, from simpler bodies. If we succeed in 

 proving that the green cells of C. roscoffeusis possess 

 these powers, other problems will present themselves. 

 Thus, we shall want to know, what are the green 

 cells? Is C. roscoffensis born with them or does it 

 acquire them ? If it acquires them, how do they get 

 into the body and what are they like before they 

 become constituents of the body of the animal ? 



As a preliminary to the investigation of these and 

 other problems on the origin, significance and fate of 

 the green cells, we will turn back to consider further 

 the behaviour of C. roscoffensis and C. paradoxa with 

 respect to food. The various observers who have 

 occupied the-mselves with investigations into the 

 mode of life of C. roscoffensis have all reached the 



K. 6 



