360 JOHN F. FULTON, JR. 



Zooxanthella and described the species from CoUozoum inerme as 

 Z. nutricula. He confirmed and extended his observations in 

 later papers (Brandt, '82, '83). In the latter paper ('83) he 

 observed that if Sagartia or Aiptasia are put in the dark for three 

 days, they extrude all of their yellow cells, and if subsequently 

 put into filtered sea-water they continue to live uninfected by the 

 Zooxanthellae. Though Keeble and Gamble ('07, p. 171) cast 

 doubt upon the accuracy of Brandt's experiments, the writer has 

 himself observed that Condylactis passiflora lost its yellow cells 

 after two days in darkness (as indicated by the loss of color of the 

 tentacles), and that three days were required for reinfection, even 

 in unfiltered sea-water. Moreover, many authors (Beyerinck, 

 '90; Famintzin, '89, '91; Dantec, '92; Dangeard, '00, and Keeble 

 and Gamble, '07) have reported having made cultures of parasitic 

 algae taken from protozoans, actinians, and turbellarians. The 

 authors last mentioned (Keeble and Gamble) have made a 

 thorough-going investigation of the green and yellow cells of the 

 turbellarian worms Convoluta roscoffensis and C. paradoxa, and 

 their results demand very careful consideration (Gamble and Kee- 

 ble, '03; Keeble and Gamble, '05, '07; Keeble, '08, '10). 



Convoluta roscoffensis is a slender green worm peculiar to the 

 coasts of Brittany. It occurs in 'spinach-green' patches, and has 

 as a distinguishing feature of its ecology the habit of sinking at 

 night below the surface of the sand, coming out only during the 

 sunlight. Previous investigators (Geddes, '79 a, '79 b; Haber- 

 landt, '91, and Georgevitch, '99) had concluded that Convoluta 

 ingested no solid food of its own, but that is depended entirely 

 upon the nutritive substances supplied by the green algae; they 

 believed, that is, that in C. roscoffensis there exists a condition 

 of true photosynthetic symbiosis. Gamble and Keeble, however, 

 have found after many careful experiments that before maturity 

 Convoluta 'feeds and feeds voraciously.' In contradiction to 

 the observations of Geddess and of Haberlandt, that the green 

 worm dies after three days in a dark room, they find that Con- 

 voluta is able to remain in darkness for more than a fortnight. 

 They observe, moreover, that the starch from the green cells 

 disappears only with great slowness during the confinement. 



