PLANKTON DIATOMS 



OF THE GULF OF CALIFORNIA OBTAINED BY THE 



G. ALLAN HANCOCK EXPEDITION OF 1936 



By W. E. ALLEN 

 Scripps Institution of Oceanography- 

 University of California 

 La Jolla, California 



Introduction 



The Gulf of California has attracted the attention of seafaring 

 people, oceanographers, geographers, and geologists for a long time. 

 Its peculiarities of form and its situation are alone sufficient to de- 

 mand notice. In addition, its connective relation between the outlet of 

 one of the large drainage systems of North America and the ocean, 

 through an arid region for hundreds of miles, suggests many prob- 

 lems in numerous fields. Furthermore, some observers say that the 

 resemblance of certain organisms in the Gulf to some of those char- 

 acteristic of Atlantic seas suggests important problems in its geo- 

 logical history. 



Notwithstanding such stimuli to attention and interest, very little 

 authentic information about the Gulf is in existence. We know that 

 its general dimensions are over seven hundred miles in length, about 

 sixty miles in width, and that its depth exceeds a thousand meters 

 in more than one half of its length, but we do not know details of 

 differences (cyclical or noncyclical) in physical, chemical, and bio- 

 logical conditions which exist within its extent. 



Many people have known about the opportunities for investigators 

 in these waters, but few have tried to do anything about it. Captain 

 G. Allan Hancock is one of those who has really done something 

 about it. In February and March of 1936 he added the surface col- 

 lecting of microscopic plankton organisms (mainly diatoms in this 

 case) to his other scientific observations and Investigations. This 

 report gives the more important results of study of the collections 

 obtained at that time. 



Diatoms are microscopic plants which may be found in water or In 

 wet spots almost anywhere. Sometimes they appear as brown, slimy 

 masses of velvety material under the drip from a leaky hydrant. 



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