iv] GREEN CELLS OF CONVOLUTA 129 



are unicellular, bear flagella of equal length and store 

 their reserve food-material in the form of starch ; 

 they possess each an eye-spot, a pyrenoid and a cup- 

 shaped chloroplast, enclosing a core of colourless, 

 nucleated protoplasm. The only important respect in 

 which the infecting organism differs from a typical 

 chlamydomonadine cell is that, whereas the cell- wall 

 of the latter consists of cellulose, that of the former 

 has not given in our hands the reactions indicative 

 of this substance. 



Carteria, a genus of the Chlamydomonadinese is 

 characterised by the possession of four flagella, and 

 so also is one species of Chlamydomonas (C. multifilis). 

 Therefore the infecting organism should perhaps be 

 referred to one or other of these genera. Or it may 

 be that it belongs to a yet lower group. These are 

 matters, however, for the systematist to decide. 



What is certain is that the green cells of the body 

 of C. roscoffensis once saw independent days, and 

 that, for those cells, naked and deprived of nuclear 

 material, these independent days are gone never to 

 recur. 



K. 



