THE BIONOMICS OF CONVOLUTA ROSCOFFENSIS. 419 



We couclude — 



(1) That Convoluta has not lost its power of independeut 

 nutrition. 



(2) That the animal obtains little if any food by the 

 translocation of the reserves of its green cells. 



(3) That the sand in which Convoluta lives is not barren 

 of other life, as von Graff supposed, but that it supports a 

 rich and varied flora and fauna. 



We have demonstrated the dependence of starch-formation 

 in the green cells on the presence of light, by maintaining 

 animals in darkness till all reserve starch has disappeared 

 and then exposing them to light. Starch makes its appear- 

 ance in the green cells after less than ten minutes' exposure 

 to bright sunlight. 



By the use of monochromatic screens, we show that the 

 rays which are most active are — as in plant chloroplasts — 

 those between B and C (Fraunhofer lines) ; that no assimila- 

 tion (as measured by reserve starch) takes place in the 

 green ; that some occurs in the blue. The spectrum of the 

 alcoholic extract of chlorophyll of Convoluta, examined 

 by the hand-spectroscope, shows the chief absorption band 

 of chlorophyll (between B and C) and strong absorption of 

 the blue end. 



2. Development of the Green Cells. 



A. General. — Direct proof that the green or yellow cells 

 of Protozoa, Coelenterates, Turbellaria, and other animals 

 are due to an infection from without has been obtained only 

 in the cases of sea-anemones (Brandt), Hydra viridis, and 

 Stentor (Beyerinck and Faraintzin). The pure cultures, in 

 the latter cases, have been identified with the green alga, 

 Chlorella vulgaris. A similar origin by infection is 

 assumed for the green cells of other animals, and the rela- 

 tion is generally regarded in all cases as a symbiosis. 



B. Previous Observations. — With respect to Con- 

 voluta, Haberlandt failed to cultivate the green cells. 



