538 DISCOVERY REPORTS 



SUMMARY 



Thirty-five records taken with the Continuous Plankton Recorder in oceanic regions 

 are described and these demonstrate marked fluctuations in the distribution of the main 

 planktonic groups of animals. 



These spatial fluctuations appear to be no less marked in the tropics than in the 

 Antarctic Zone. 



The types of distribution shown by different groups are discussed. 



The existence of a rhythm in the distributional fluctuations is tentatively suggested, 

 a rhythm which varies on different occasions. 



REFERENCES 



Haeckel, Ernst, 1890. Plankton Studien. Jenaische Zeitschrift, xxv, and translated by G. W. Field as 

 Appendix 6 to the Report of the Commissioner for 1889 to 1891, United States Commission of 

 Fish and Fisheries, Washington 1893, pp. 565-641. 



Hardy, A. C, 1926. A new method of plankton research. Nature, cxvili, p. 630. 



1936. The Continuous Plankton Recorder. Discovery Reports, XI, pp. 457-510 



Hardy, A. C. and Gunther, E. R., 1935. The Plankton of the South Georgia Whaling Grounds and Adjacent 

 Waters, 1926-7. Discovery Reports, XI, pp. 1-456. 



