Hida (1954) found a greater abundance during 

 May (unadjusted average = 15.9 cc./l,000 m."^) 

 than in August (unadjusted average = 12.6) for 

 1950. For 1951 they found a significant differ- 

 ence between July (adjusted average = 25.6 and 

 October-November (adjusted average = 20.3). 



The seasonal variations in the middle stratum 

 (table 4) do not follow those of the upper layer. 

 Discrepant results such as these make uncertain 

 the significance of data on seasonal fluctuations, 

 particularly since annual variations may mask 

 seasonal variations. 



Variations in Composition 



Plankton counts were made on all samples 

 in the comprehensive series to detect gross 

 changes in composition. Identification was only 

 to general categories (table 9); further identifi- 

 cation was considered impractical. A few cate- 

 gories represented in the collections are not 

 listed in the tables because they composed such 

 small percentages of the total count. Colonial 

 forms and fragile organisms such as radiolar- 

 ians, siphonophores, and polychaetous annelids 



Table 9. --Percentage composition and average number of organisms per 1,000 m.^ of water 

 strained by the upper net on the Smith cruises and by the net towed between the surface 

 and the top of the thermocline on CHG-24 



Item 



Cruise 



CHG-24 



HMS-32 



HMS-34 



HMS-35 



HMS-36 



Cruise period 

 Number of samples 

 Number of day hauls 

 Number of night 



hauls 

 Number of twilight 



hauls 

 Avg. sample vol. 



(cc./l,000 m.3) 

 Avg. adjusted vol. 



(cc./l,000 m.3) 



Nov . 



Organism 



Number per 

 1,000 m.3 



Per- 

 cent- 

 age 



Number per 

 1,000 m.3 



Per- 

 cent- 

 age 



Number per 

 1,000 m.3 



Per- 

 cent- 

 age 



Number per 

 1,000 m.3 



Per- 

 cent- 

 age 



Number per 

 1,000 m.3 



Per- 

 cent- 

 age 



