3 i6 



DISCOVERY REPORTS 



WIND 



DRIFT 



LEFT-HANDED 



DRIFTS TO RIGHT OF DOWNWIND 



STARBOARD TACK 



RIGHT-HANDED 



DRIFTS TO LEFT OF DOWNWIND 



PORT TACK 



Text-fig. 5. Physalia physalis. Angle of drift from the windward direction of left- and right-handed 



specimens. PZ = protozooid. 



Text-fig. 6. Physalia physalis. Direction of drift, a, b, c, to show why the drift is not normally straight down-wind. 

 d, to show an apparent movement into the wind caused by drift of the surface water to leeward. 



