198 F. KEEBLE AND F. W. GAMDI-E. 



association of ^'attendant nucleus " and green cell is sliown 

 in PI. IS, fig. 9, Nu. il/f'.s\ Farther investigation of tliis 

 phenomenon is required ; hut such observations as we have 

 made point to the belief that these attendant nuclei are those 

 of wandering cells which lie in wait^ as it were, for enucleate 

 green cells and at a subsequent stage bring about their 

 destruction by digesting them. 



The foregoing, interpretation of the series of facts described 

 offei-s some support in favour of the hardy suggestion, due 

 originally to Schimpcr,^ that the higher green plants arc an 

 association of two organisms — one a colourless organism, the 

 other originally a green alga but now represented by the 

 chloroplasts and by them alone. 



For an adult Convoluta is a complex of two organisms — one 

 the coloui'less animal, the other the chloroplast remainders 

 of the original green alga; but in this case, unlike that 

 imagined for the green plant, the synthesis is not a perma- 

 nent one. It endures but for the lifetime of the animnl and 

 has to be recommenced in every larval Convoluta. 



Summary of Section Y. 



(1) The colourless phase of the infecting alga normally 

 supplies the cells which develop in the body of Convoluta 

 into the green-celled tissue, which tissue is comparable witli 

 the pal mel la-stage of the alga. 



(2) But infection may also result from the ingestion of the 

 green active or green temporarily resting-cell. 



(3) Ingestion is followed by the active division of these 

 cells Avhicli develop transient eye-spots, etc., but which do 

 not form a cell- wall. 



(4) 'J'he distorted shapes of the green cells in the animal 

 are due to osmotic conditions. 



(5) The nucleus of the green cell dividing in the animal 

 undergoes progressive degeneration and finally disappear, 

 leaving the photosynthotic machinery intact. 



' ' Bot. Zeit.,' 1883, p. 112, foot note. 



