418 F. W. GAMBLE AND FRKDERICK KliEBLE. 



meiit of the eyes^ take place dun'n,^ the first two or three days, 

 and afford a useful mark by which such larvae may be readily 

 distinguished from just hatched Convoluta. Under natural 

 conditions the food of young Convoluta consists of sdgsd, 

 diatoms^ and other organisms, as described on p. 370. The 

 evidence that from such a mixed infection Convoluta pro- 

 duces a pure culture of ''green cells," digesting the remainder, 

 is given in Sect. III. 



Section VI. — Summaky. 

 1. Food. 



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, 

 von Graff, and Haberlandt 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 by 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, Convoluta (1 to 5 mm. 

 long) ingests diatoms, algae, spores, grains of sand, and 

 colonies of bacteria. It also takes up such substances as 

 litmus, congo-red, etc., with avidity. Mature and immature 

 specimens digest masses of their own green cells, the dis- 

 coloured remains of which form conspicuous brown clumps 

 in the gut. 



Moreover we have maintained Convoluta alive in com- 

 plete dai'kness for more than a fortnight, and find that the 

 starch of the green cells disappears with extreme slowness 

 — not till after five days of dai'kness in young (1 to 2 mm. 

 long) animals; seven days iu adults. 



