420 F. W. GAMBLE AND FREDERICK KEEBLE. 



Observing tlieir remarkable histological features (absence of 

 cellulose wall, etc.), be put forward the hypothesis that the 

 green cells are now parts of the animal — animal cells to 

 which a leucoplast is transmitted from the egg. 



Georgevitch hatched out Convoluta, showed that it 

 develops as a colourless larva, and claims that such a 

 colourless larva, if kept in sterilised water, fails to develop 

 green cells, and dies within two days. He concluded that 

 the green cells gain access to the animal from the sea water. 



c. Experiments of the Authors. — Our experiments 

 lead us to the following conclusions : 



(a) A leucoplast cannot be detected in the egg. 



(b) Convoluta hatched in sterilised water may live for 

 two weeks therein. 



(c) The first indication of the future green cell is colour- 

 less, and not green. Infection, if it occui', is by a colourless 

 cell. 



(fZ) The precautions to ensure sterile conditions, taken by 

 Georgevitch and by ourselves in our earlier experiments, are 

 useless. In these experiments the egg-capsule was placed 

 in sterilised water ; we find, however, that the egg-capsule 

 bears a rich and varied collection of green, pale green, and 

 colourless cell colonies. 



(e) Contrary to Georgevitch's statement, when hatched 

 from egg-capsules placed in sterilised water, Convolutas 

 are found in a certain number of cases to develop green 

 cells. Hence either the green cells are not the result 

 of infection, or infection may take place from the capsular 

 flora. 



(/) The latter alternative is probably correct, for the 

 more precautions are taken to protect larval Convoluta 

 from infection, the fewer are the cases in which green cells 

 or their colourless antecedents make their appearance in the 

 animals. 



(g) The colourless antecedents of the green cells are first 

 seen in the gut, just above the mouth. 



D. Conclusions. — Direct proof of infection is lacking. 



