20 University of California Publications in Zoology [Vol. 22 



the area of the inlet to the net. Before using, the net was placed in 

 warm, soapy water and gently rinsed in order to induce uniform 

 shrinkage. 



The drain cup was removed after each haul and the contents washed 

 off into a small pail. Some organisms clung very tenaciously to the 

 net and vessels. This was especially true of the stentors and some 

 rotifers. The water in the pail was strained through a silk cup at 

 the end of the collection. 



The Amount op Haul 



The standard collection covered an aggregate haul of twenty-five 

 meters. Sometimes it was not possible to make a full collection. On a 

 few occasions the light was too poor to make a full midweek collection. 

 At these times it was usually possible to take half the usual haul. On 

 still fewer occasions the silt clogged the net so badly in the river that 

 only about one-fifth of a standard collection was taken. Even so it 

 seemed that the net would surely break before it drained. Drainage 

 of the net was always hastened by shaking the net slightly or by 

 working it with the fingers. 



Most hauls at Station I were at the depth of three meters ; at Station 

 II, fo.ur meters, and at Station III, two meters. Sometimes fr e meters 

 could be taken at Station II. On the other hand there were times 

 when only one meter could be taken at Station III. Most hauls in the 

 river were taken while drifting. Most hauls in Stockton Channel and 

 Smith Canal were taken while at anchor. Except on one occasion all 

 hauls were made by the same person. The net was always hauled as 

 nearly as possible at such a speed that it would just fail to throw water 

 from its mouth as it broke the surface. This was about one-half meter 

 per second. All hauls were as nearly vertical as possible. No par- 

 ticular effort was made to get in midstream at any time. In fact some 

 collections were taken near the bank because of deeper water there. 

 A few collections were taken from boat landings when the writer's 

 motor boat was not in working order. 



Records 



Records were kept of the temperature of air and water at each 

 station. The air temperature was taken first and it was always taken 

 in the shade without much motion. The water temperature was taken 

 by holding the bulb from one to three inches below the surface of the 



