322 DISCOVERY REPORTS 



nineteen were left-handed and three were right-handed, that is 86% of them were mirror-images of 

 the animals from the northern hemisphere '. We must know whether and how frequently animals of 

 either tack can in theory come ashore with winds that occur on beaches for which records are 

 available. 



Once more I have pleasure in acknowledging my indebtedness to Mr J. C. Natzio for reporting to 

 me observations made aboard R.R.S. 'Discovery II ' in the vicinity of 38 35' N., 20 13' W. in the 

 middle of March 1958. The ship was frequently stopped and it was possible to keep Physalia indivi- 

 duals in view for some time. On a typical occasion the ship was lying-to with the wind north-west, 

 force 2, on the port beam. The ship was drifting to leeward at about \ a knot and the speed of drift 

 of Physalia specimens was estimated at about \ of a knot in a direction to the left of down-wind. The 

 angle between the animals' course (drift) and the direction of this force 2 wind was about 40 , the 

 maximum observed. In winds stronger than force 4 the line of the floats' crests was parallel to the 

 wind's direction and the animals drifted straight down-wind. Natzio doubted whether Pkysalia 

 drifted any faster under these conditions. Physalia, he said, is quite easily blown by a slight gust so 

 that the blunter, oval end is temporarily ahead, and the animal may sail in this way for some little 

 distance. He also reported that rolling appeared to be slow and deliberate in calm weather, while 

 in a wind the animals seemed to be suddenly blown straight over until the crest was horizontal on the 

 surface of the water. He got the impression that capsizing was caused by a sudden gust upsetting the 

 stability of the float, and not as I suggested by a lull, for he observed a float to be blown apparently 

 straight over on the water where it would remain for some seconds, after which it would flick back 

 suddenly into the upright position again. In my opinion this behaviour does not constitute the rolling 

 phenomenon. Natzio likened the appearance of Physalia to that of a buoy with a tide running past it, 

 the tentacles functioning as the buoy's mooring cables; they have the same retarding effect as that of a 

 sea-anchor. 



During this spring cruise of ' Discovery II ', Natzio reported, Physalia was seldom absent from view 

 south of about 38 30' N. As a rule one specimen was not out of sight before others came into view. 

 The maximum float-length observed would have been about 7-8 in. A swarm might consist of more 

 than a hundred in an area of as many square yards, and the individuals in a swarm varied in size from 

 the maximum down to as little as an inch or so. The average length was perhaps about 4-5 in. Very 

 small ones could easily have escaped observation. Apart from the swarms, Natzio's impression was 

 that Physalia was quite widely scattered. 



Stinging-powers and Toxicology 

 It appears from various published accounts that there is a complex mixture of pharmacologically active 

 substances in the tentacles of the Cnidaria, not all of them necessarily confined to the stinging-capsules 

 or nematocysts. It is not surprising, therefore, that the effects of being stung by these animals, or of 

 injecting extracts, are varied. In addition some nematocysts have greater powers of penetration than 

 others. Lane and Dodge (1958) report that tentacle-nematocysts of living Physalia may occasionally 

 penetrate heavy-gauge surgical gloves. Attempts have been made to identify the substances which 

 produce the stinging sensation and other effects, but until quite recently all the cnidarian substances 

 used for experimental work have been obtained from crude tentacle-extracts. Fortunately new 

 techniques are now available (Phillips, 1956; Lane and Dodge, 1958) for obtaining pure capsular 

 contents. 



As to the effects of being stung by Physalia I know of no records of fatalities, but as Elizabeth Pope 

 ( J 953) has pointed out there has been some confusion in Queensland between Physalia, to which the 

 name Portuguese man-of-war should be strictly confined, and a very dangerous Charybdeid jelly-fish 



