258 



DISCOVERY REPORTS 



lines before 0300 o'clock may represent the upper edges of larger swarms below not yet 

 risen into the line of observation. Similarly, in this species we may be observing patches 

 at the top of a wave of vertical migration. 



Station 41. Here we have evidence of patchiness regarding some of the smaller 

 organisms obtained in quite a different way. 



5Ch BEROE 



B0 CALANUS PROPINQUUS 



40- 



150-1 PAREUCHAETA ANTARCT/CA 



100- 



50- 



300 1EL/PHA US/A PRIGIDA 



Fig. 131. Histogram showing the variations in the numbers of several plankton animals taken in twenty- 

 three consecutive surface hauls with N 100 H nets {A-X) at St. WS 53. 



As has already been explained in the earlier section on vertical migration, the ' Dis- 

 covery' anchored in 272 m. of water at St. 41 , 16 miles off the north-east coast of South 

 Georgia, in an attempt to carry out repeated observations on the plankton throughout a 

 period of 24 hours. The object of this experiment was primarily to study the vertical 

 migration of the plankton, but also to obtain a series of observations which would to 



