1922] Allen: Studies on Diatoms and Dinofiagellates 377 



SUMMARY AND CONCLUSION 



1. It is certain from the excellent condition of the series from 

 Pt. Hueneme that a trustworthy untrained man can do satisfactory 

 work in plankton collecting by our measured water method. 



2. As is shown in table 1 the average number of diatoms is much 

 greater through most of the year than is the average number of dino- 

 fiagellates. The ratio at La Jolla was nearly 1/15 and at Pt. Hueneme 

 nearly 1/8. Actual nutritive values of the two popidations may have 

 been somewhat similar. 



3. As is shown in the discussion of morning and evening catches, 

 the behavior of diatoms and dinofiagellates is not enough alike to 

 warrant my former practice of discussing them together as a photo- 

 synthetic assemblage, since the morning catches of diatoms exceeded 

 those of the evening while the evening catches of dinofiagellates 

 exceeded those of the morning. 



4. The studies of this year have yielded continued evidence that 

 distribution of organisms in sea water is not uniform. 



5. Seasonal variations in numbers at La Jolla did not closely 

 accord with the probabilities mentioned by various observers since a 

 period of sustained productivity came much earlier than might have 

 been predicted in the case of both diatoms and dinofiagellates. There 

 was also some indication of such departure at Pt. Hueneme. 



6. At neither station was there much variation in the kinds of 

 diatoms and dinofiagellates according to time of year. There was 

 some suggestion of the possibility that two or three forms are rela- 

 tively stable and constant and that one or two other forms may gain 

 prominence through marked responsiveness to seasonal differences. 



7. From my experience in the study of this series it is increasingly 

 evident that we not only need long, continuous series of observations 

 in as many localities as possible but that we greatly need enormous 

 increase of such observations in many complementary and supple- 

 mentary lines. 



