THE BIONOMICS OF CONVOLUTA ROSCOFPENSIS. 417 



prolonged. During tins phase tlie animal is flexed ventrally, 

 both longitudinally and transversely. The otocystis present, 

 the Avail being lined witli fatty globules. The whole body is 

 full of similar fatty granules of vai'ying size, which granules 

 stream inwards and outwards in obedience to muscular con- 

 traction, The epidermal orange-red glands are already 

 present. The eyes, however, are indistinguishable. Very 

 characteristic of the revolving phase is the presence near the 

 hinder end of the body of a large coloured vacuole, brown or 

 yellowish. It lies ventrally in a nucleated meshwork, the 

 foundation of the inner parenchyma or gnt. Within the 

 vacuole one or more refractive fatty globules and spicules of 

 unknown significance are frequently found. This vacuolated 

 structure undergoes marked variations of shape ; at one time 

 it is spherical, at another irregulai'ly branched. During 

 microscopical examination it frequently collapses, and its 

 contents immediately disappear. This coloured vacuole is 

 found, though less sharply defined, in just hatched Con- 

 voluta, disappearing after the first day or two. 



When the young Convoluta is ready to hatch out, the 

 egg-membrane splits equatorially (PI. oU, fig. 3 b). The 

 society of larvas, after creeping and swimming within the 

 capsule, suddenly leave it, passing with ease through the 

 thin walls, to which they frequently return after a short spell 

 of activity. As we have pointed out in Sect. II, there are 

 good grounds for believing that the food of Convoluta is 

 supplied by the varied organisms living on and in the egg- 

 capsule. For days, however, isolated larvfB will live in 

 sterilised water, developing at the expense of the fat with 

 which their tissues are supplied. As this fat is gradually 

 absorbed from the 'Mnner parenchyma" or gut, this tissue 

 contrasts more strongly than before with the still fat-laden 

 peripheral parenchyma (PL 31, fig. 15). Ultimately, if 

 no food is supplied, the Convoluta becomes more and more 

 vacuolated, exhibiting phenomena of starvation very similar 

 to those described by Wallengren (1902) in Paramecium. 



The disappearance of fat from the otocyst, and the develop- 



VOL. 47, PART 3. — NEW SEKIKS. DD 



