

Foraminifera 93 



green algae for food, such as Spirogyra, Zygnema, Mougeotia, and 

 Oedogonium. 



Culturing may be carried on in almost any type of container, though 

 the shallow types usually give best results. 



Spring, pond, or tap water may be used, with preference in the order 

 named. The pH should be between 6 and 7.3. If small containers, 

 depression slides, etc., are used over long periods of time, the water must 

 be changed frequently (every 2 to 3 days). Larger cultures in petri 

 dishes may be run a week to 10 days. 



Cultures should be kept out of direct sunlight and below 22 C. if 

 possible. Small amounts of fine sand should be provided in cultures of 

 D. oblonga, D. constricta, and D. lobostoma for shell construction. 



Order foraminifera 



CULTURE METHODS FOR MARINE FORAMINIFERA 

 OF THE LITTORAL ZONE 



Earl H. Myers, Scripps Institution of Oceanography 



ALTHOUGH the Foraminifera are universally distributed in the sea 

 l and have been the subject of investigations for more than 200 

 years, comparatively little is known concerning their methods of repro- 

 duction, or of those physiological factors which limit the geographical 

 and bathymetric distribution of these organisms (Myers, 1934). Con- 

 fusion in the systematic designation of species is frequently due to 

 their changing morphology which is the result of an alternation of gen- 

 erations, growth stages, a response to environmental conditions, or 

 parasitism. In any attempt at a natural classification of these poly- 

 morphic forms, it is necessary to recognize their genetic relationship, and, 

 where it is possible, their biological explanation should be determined. 

 The solution of many of these problems can best be approached by means 

 of laboratory cultures. Many species of the littoral zone may be main- 

 tained in cultures with a minimum of effort and without the use of 

 running seawater. Therefore, this field of investigation offers a splendid 

 opportunity for original work to anyone who has access to the sea and 

 has acquired a reasonable amount of skill in microscopic technique. 



In selecting a problem in this field, time is an important factor to take 

 into consideration, due to the low rate of reproduction in this group as 

 compared to other Protozoa. Growth in the majority of polythalamous 

 species is a discontinuous process, because of an alternation of a vegeta- 

 tive phase with the addition of each newly formed chamber. In small 

 species of Discorbis, where the test is composed of a continuous series of 



