436 



University of California Publications in Zoology [Vol. 22 



GENERAL DISCUSSION 



As in 1921, it was found that diatoms were distinctly more numer- 

 ous than dinoflagellates throughout the May-June period in almost 

 all catches at the various levels (table 1). The trend of distribution, 

 however, was very similar in the two groups. Dinoflagellates as well 

 as diatoms were fairly numerous in the catches when the series was 

 first begun on May 18 and, like the diatoms, they decreased somewhat 

 in numbers until about the middle of June, when increase in both 

 groups occurred rather suddenly. This similarity was roughly true 

 at all three levels. The range of change in production was greatest 

 at the surface and the twenty meter levels (figs. 1 and 2, Station I and 

 Station II). 



TABLE 1 



Table to Show Average Number per Liter of Diatoms and Dinoflagellates 



in Samples of Sea Water from Three Depths at 



Stations I and II, 1922 



May-June 



Station I Surface 20 meters 40 meters 



Number of catches 34 31 33 



Average per liter 



Diatoms 13,731 48,739 3,393 



Dinoflagellates 416 267 143 



Station II 



Number of catches 34 31 31 



Average per liter 



Diatoms 15,249 52,226 7,409 



Dinoflagellates 2,425 275 146 



September 

 Station I 



Number of catches 11 11 9 



Average per biter 



Diatoms 41 39 245 



Dinoflagellates 432 152 763 



Station II 



Number of catches 11 11 10 



Average per liter 



Diatoms 170 653 7,220 



Dinoflagellates 4,341 366 333 



In spite of such similarities as those just mentioned, it has been 

 decided that the two groups have not enough in common to be accept- 

 ably treated as a general population of photosynthetic organisms. 



