534 



discovery reports 

 Record 35 



Dates: 20-21. viii. 27. 



Time: 1800-0530. 



Position: oi° 50' S, n° 15' W to oi° 07' S, 13 12' W. 



Distance by ship's log: 75-6 miles. 



These two records were taken on the homeward voyage of the R.R.S. 'Discovery' 

 just south of the equator (see Fig. 1). The fluctuations in the Copepoda, Chaetognatha, 

 and young Euphausiacea are shown for both records in Fig. 17, and in addition in 

 RECORD 34 RECORD 35 



lOOCh 



LABIDOCERA ACUTIFRDN5 

 ...l I l I. J .i.l.l .1 1....I- i/. i-.l 



500 



COPEPODA 



10 

 J 





 l5 °i EUPHAUSIACEA juv. 



1003 

 SO 



100 



50 



CHAETQ 

 GNATHA 



— 1 1 - 



5 



10 



▲ 



HOUR a 



and £ 



DATE a 



AUG. 19. 



▲ 



o 

 o 



CD 



RECORDER SECTIONS 

 ▲ 



AUG. 20. 



a 

 o 

 00 



-1 1 1 r- 



10 



Q 

 O 

 O 



a 



15 



20 



AUG. 21. 



O 

 n 



in 

 a 



Fig. 17. Variations in the numbers of the predominant plankton organisms on Records 34 and 35 taken along 



distances of 40-7 and 75-6 miles respectively. 



record 35 are shown the numbers of Diphyidae and the copepod Labidocera acutifrons. 

 Isolated specimens of ostracods, amphipods, pteropods, small cephalopods, young fish 

 and salps are not shown. 



DISCUSSION 

 First of all it is necessary to be satisfied that the fluctuations observed are real ones in 

 the sea and not an artifact due to an erratic behaviour in the recording mechanism. 

 Usually a failure in the mechanism results in a complete stoppage, but occasionally the 

 winding may continue for a time at a slower speed before stopping ; but such failures are 

 exceptional and detectable (see record 15 in Fig. n). A consideration of the records 

 obtained shows clearly that the fluctuations cannot be due to mechanical irregularities ; 



