1922] Allen: Studies on Marine Phytoplankton at -La Jolla 331 



LOCATION 



The Scripps Institution lies in approximately 32° 50' north lati- 

 tude and 117° 15' west longitude. It is about two miles distant from 

 the village of La Jolla, near San Diego, California. Other marine 

 localities in about the same latitude are Charleston, South Carolina, 

 the Bermuda Islands, the Madeira Islands, Alexandria (in Egypt), 

 and Shanghai, China. Very little study has been made of either 

 marine or fresh-water plankton in or near this latitude, and there is 

 practically no other series of collections of phytoplankton fairly com- 

 parable with the one now under discussion. Hence it is necessary 

 when comparing with other work to bear in mind the markedly 

 different geographic conditions. The water temperature at the pier 

 varies from about 13° 0. in January to about 23° C. in August. 

 Water at the outer end of the pier is about 27 feet deep at high tide. 



EQUIPMENT AND METHODS 



T have in preceding papers (Allen. 1921 b and c) made brief 

 statements concerning our standardized methods of collecting and 

 handling material; those who desire more detailed information may 

 obtain it by writing to The Director, Scripps Institution for Bio- 

 logical Research of the University of California, La Jolla, California. 



THE MATERIAL 



Marine phytoplankton in temperate regions consists mainly and 

 essentially of diatoms and dinoflagellates. The material obtained at 

 our pier is typical in this respect. It is all microscopic. 



General Discussion 



The regular series of catches at twelve hour intervals was begun at 

 8 a.m. on September 1, 1919. The new short net which was then put 

 in use had been slightly shrunken and clogged by being used for 

 making extra catches. In spite of this there was undoubtedly some 

 loss of small forms through the meshes. 



