344 M or pho genetic Factors 



Margalef ( 1953 ) found that in cultures of the green alga Scenedesmus 

 obliquus low temperatures cause cell size to increase, although other fac- 

 tors have a minor effect on it. Since cells in this species grow faster 

 in length than in width, large cells have a more slender shape than 

 small ones, so that temperature indirectly affects cell shape. 



