Cytology and Movements of the Cyanophyceae. 239 



port living organisms. No other class of plants can exist 

 under such varied surroundings, though each species is most 

 delicate in its response to its own environment. In the hot 

 springs of the Yellowstone National Park, where the water 

 reaches 190° F., the boiling point at that altitude, these are 

 the only organisms that can find the necessary conditions of 

 existence. They range from such conditions through all 

 temperatures to the frozen seas of the North, and though 

 the waters be strongly impregnated by alkaline salts or acids, 

 the organisms are not yet excluded. It is just such environ- 

 ments that one would expect to find in the beginning of the 

 earth's phytological history, and it seems reasonable to con- 

 sider these organisms as the surviving basis of a phytolog- 

 ical tree. Their power of elaborating food in the dark as 

 claimed for the Cyanophyceae by Hansgirg, and their abil- 

 ity to withstand long periods of drying which will shrink 

 their cells to one-third of their natural size while still retain- 

 ing their vitality, would also be in favor of their primitive 

 origin. 



There are many cytological problems locked up within 

 the cells of the Cyanophyceae, but in the past investigators 

 have mostly confined themselves to the questions of the pres- 

 ence of nuclei and chromatophores. These still constitute 

 the fundamental questions which must be confronted. Palla 

 (60) thus sums up the situation in this respect: "We have 

 three possibilities before us, either (a) the Cyanophycean 

 protoplasts have true cell nuclei, whose significance we have 

 not known up to the present time, or (6) the nuclei of the 

 progenitors of the Cyanophyceae have been reduced until 

 they have entirely disappeared, or (c) the Cyanophyceae 

 are without nuclei." Though the present investigation does 

 not confine itself to the nuclear side of the problems, never- 

 theless this phase of the subject must necessarily receive 

 much attention. It was therefore with much interest that 

 the subject in hand was entered upon at the suggestion of 

 Professor Macfarlane, who has watched the different steps 



