444 University of California Publications in Zoology [Vol. 22 



changes in magnitude of the catches. This connection is obvious when 

 comparing the graphs in figures 1 and 2 with those in 3 and 4. From 

 mid-May to nearly mid-June there was fairly consistent decrease in 

 production of diatoms at both stations and at all levels. The third 

 week in June brought a rapid rise, followed in the fourth week by an 

 equal decrease. Surface temperatures had been consistently rising 

 and twenty and forty meter temperatures had varied consistently 

 about a mean up to the third week in June, when there was a marked 

 reduction at both stations at all levels. Pier temperatures varied 

 along lines similar to the surface temperatures. 



Temperatures. Station Z. 



Kofoid Bottle Catches - 1922 -i^au.June 



Jur/sce 



20 tffr/W 



40 Wet-OrS- oo.oooooooooco 



"■*? 



..-^ 



J 



^r 



rig. 4 



This showing of larger catches in lowered temperatures is contrary 

 to what was noted in 1921, when the principal increase in catches 

 came close to rising temperatures (although the largest single catches 

 were made in reduced temperatures, Allen, 1923, pp. 78-79). While 

 such contradictory results make it very difficult to see the mode or 

 extent of direct influence of temperature, they do not weaken the 

 view that temperature is in some way a leading factor. Furthermore, 



