1903.] TJtr Bionomics o/ Convoluta Roscoffensis, etc. 93- 



" The Bionomics of Conwluta Roscoffensis, with special Reference 

 to its Green Cells." By F. W. GAMBLE, D.Sc., Owens- 

 College, Manchester, and FKEDEKICK KEEBLE, M.A., Uni- 

 versity College, Reading. Communicated by Professor S. J. 

 HICKSON, F.R.S. Eeceived April 24, Head June 18, 1903. 



The communication is an abstract of our observations on the 

 Bionomics of Convoluta JKoscoffetisis, the green Turbellarian peculiar to- 

 the coast of Brittany. 



A detailed illustrated account of these observations will be published 

 shortly. The work was begun at Roscoffin 1901, and has been carried 

 on since at Tregastel (C6tes du Xord), and in the laboratories of Owens 

 College, Manchester, and University College, Reading. It contains the 

 following sections : 



1. Food; 2, Development of the Green Cells; 3, Tropisms ; 4, 

 Ecology. 



IFood. 



A. Previous Observations. Previous observers have failed to demonstrate 

 the presence of ingested solid food in either the larval or adult stage of 

 Convoluta. Geddes, 1 Von Graff,- and Haberlandt, 3 concluded that 

 Convoluta does not feed, but that the animal derives its food-material 

 from the products of the photosynthesis carried on by its green cells. 



Geddes and Haberlandt were confirmed in this conclusion on finding 

 that the animal, when placed in darkness, dies in the course of two or 

 three days. 



B. Observations ly the Authors. Our observations stand in direct 

 contradiction to these. Convoluta feeds, and feeds voraciously. From 

 the time of hatching up till the time of commencing maturity, Conwluta 

 (1 5 mm. long) ingests diatoms, algae, spores, grains of sand and 

 colonies of bacteria. It also takes up such substances as litmus, congo- 

 red, i^c., with avidity. Mature and immature specimens digest masses 

 of their own green cells, the discoloured remains of which form con- 

 spicuous brown clumps in the gut. 



Moreover, we have maintained Conwluta alive in complete darkness 

 for more than a fortnight, and find that the starch of the green cells 

 disappears with extreme slmvncss : not till after five days of darkness in 

 young (1 2 mm. long) animals ; seven days in adults. 



We conclude : 



(1) that Conwluta has not lost its power of independent nutrition. 



(2) That the animal obtains little, if any, food from the reserves of 



its green cells. 



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



as Yon Graff supposed, but that it supports a rich and varied 

 flora and fauna. 



