46 



J. MYERS 



Fig. I — Flask for algal culture with inlet and outlet aeration tubes. 



in air is commonly used for aeration. The gas may be conserved' 

 by placing several flasks in series as is made possible by their 

 design. A general problem of this design is that even with high 

 (and expensive) rates of aeration the algae tend to settle out; 

 some mechanical means of agitation, therefore, becomes neces- 

 sary. In conjunction with the use of such vessels it has been 

 common practice to estimate growth in terms of cell number as 

 determined by hemocytometer counts, in terms of cell-volume as 

 determined by centrifuging in hematocrits, by weighing cell 

 crops, or by turbidimetric readings. 



It is our experience that the modified Erlenmeyer flask is a 

 poor compromise between elegance and simplicity and we have 

 preferred to make modifications in each direction. Our simplest 



