iv] GREEN CELLS OF CONVOLUTA 121 



sis, it was evident at once that they represented a 

 stage in the life history of the infecting organism. 



Fig. 19. Egg-capsule of Convoluta roscoffensis occupied by a dark 

 mass consisting of vast numbers of the "infecting organism." 

 (Magnified forty times.) 



The final proof was applied. To the vessel contain- 

 ing colourless, uninfected Convolutas, some of the 

 free, green cells were added. Within two days all 



Fig. 20. The capsule shown in Fig. 19 enlarged and compressed 

 during microscopic examination : the ' ' infecting organism " 

 escaping. 



