OCEANOGEAPHY ISELIN 267 



of a reliable photometric a^Dparatus at the Plymouth Laboratory. 

 Similar apj^aratus was made for use on the Atlantis and during the 

 summer of 1931 this was tried out on her crossing from Plymouth 

 to Boston. At 13 stations careful measurements were made of the 

 amount of light at all depths down to the limit imposed by the 

 sensitivity of the photoelectric cells used. At the same time, through 

 the use of a series of five closing nets, a picture of the vertical migra- 

 tion of the plankton was obtained which could be nicely correlated 

 with the amount of light reaching the organisms throughout the day. 

 Thus the phototropic effect can be studied at sea in much the same 

 manner as in a physiological laboratory. 



Such is a summary of the various investigations carried out from 

 the Atlantis since her launching in June, 1931. This by no means 

 represents all of the work of the Woods Hole Oceanographic Insti- 

 tution. A large number of marine problems have been attacked at 

 the laboratory, and manj^ observations have been collected by the 

 Asterias, but it has been thought best to limit this account to the 

 work done in deep water because so little is known of the problems 

 of deep-sea oceanography. 



