PHTSIOLOGT 51 



wealth of fresh problems. Although some of 

 these may be insoluble in the present state of 

 science, we ought at least to see how far we can 

 go. The whole subject is so important that we 

 can afford to neglect nothing which may help us 

 to understand the mechanism of these funda- 

 mental activities of the cell. 



Since this lecture was given additional facts 

 have come to light which have necessitated some 

 changes in viewpoint. 



The investigations of Blinks and Howe indi- 

 cate that what is here called Valonia ventricosa 

 is in reality a species of HalicystiSy which puts a 

 different face upon a part of the discussion. The 

 accumulation of dye appears to be due to its be- 

 havior as a weak base which enters the sap and 

 dissociates rather than to its combination with 

 the proteins of the sap {cf. Irwin, M., /. Gen, 

 Physiol.y 1 926-1 927, Xj 75). It seems possible 

 that the accumulation of potassium can be ex- 

 plained by assuming that it enters as potassium 

 hydrate, is converted to potassium carbonate and 



