34 Unwersiii) of California Publications in Zoolorjij [Voi.. 22 



Alqak 

 Bacteriaceae 



]\rpinbors of tliis g;roiip were unquestionably abundant both in 

 numbers and kinds, but they were very rarely retained by the silk 

 net. In fact, Spirillum undula was the only representative recorded 

 from Stockton Channel, the station most favorable for Bacteria and 

 giving most evidence of their presence. The average number there, 

 16,310, is ridiculously small in view of the general conditions and in 

 consideration of the filter paper collections which indicated a total 

 volume of catch about ten times as great as that found in the silk 

 net catches. The relatively great numbers of Cladocera and Copepoda 

 also serve to emphasize the fact that the large portion of the plank- 

 ton population is veiy freqently beyond the reach of the usual 

 methods of observation. Silk net methods can never be more than 

 suggestive of the productivity of the waters since they must deal 

 mainly with the giants of the plankton. For that reason, an extended 

 discussion of the Bacteriaceae cannot be undertaken for this series. 

 Tt might be said, however, that general conditions indicate a maxi- 

 mum production of Bacteria in late summer along with the other 

 groups. 



Bcggiatoa and Micrococcus were only recorded from Stations II 

 and III, and then only once, but they were probably common at all 

 stations. 



Schizophyceae 



Station I Station II Station III Daily Hourly 



Number of forms 18 15 15 15 7 



Average per cubic meter 1,603,4U 1,292,680 1,957,661 2,599,163 499,123 



This group was most conspicuous at all .stations in July, August 

 and September, when it gave a peculiar color and appearance to the 

 water, but it had some representation throughout the year. Anabaena, 

 Nostoc and Oscillatoria were generally most prominent. Some of the 

 smaller forms were probably represented but not identified. Some 

 small forms were also probably confused with other groups. The 

 group, as a whole, does not seem according to record to be of quite 

 so great importance as in the Illinois, but this apparent lack is doubt- 

 less due to escape through the net. The color of the water alone 

 would suggest that much of the material is lost. It is then, not only 

 safe to say that the group is valuable in furnishing food for other 



