174 FROM FISH TO PHILOSOPHER 



It is well known that men lost at sea cannot drink sea 

 water and survive, and that to do so only shortens life. 

 With the maximal osmotic concentration of human urine 

 set at a level only slightly above that of sea water, very 

 little of the water in the latter could even theoretically be 

 made available for the excretion of other urinary con- 

 stituents. About 500 cc. of sea water per day is about 

 all that can be tolerated without gastrointestinal disturb- 

 ances from the unabsorbable magnesium and sulfate. 

 This would yield a meager 143 cc. of free water, a neg- 

 ligible quantity in the face of the minimal requirement 

 of 500 cc. for urine formation, and upwards of 1500 cc. 

 for sweat under conditions of exposure to sun and wind. 

 Consumption of larger amounts would only lead to 

 diarrhea and further dehydration, and thus accelerate 

 catastrophe. 



Nor can a man lost at sea improve his position by 

 drinking urine; his kidneys are already doing the best 

 they can and the only use to which either uiine or sea 

 water can be put is to use them to cool his clothing by 

 evaporation, thereby cutting down on water loss in 

 sweat. Taking the minimal urine volume as about 10 cc. 

 per gram of protein metabolized, eating raw fish will not 

 ameliorate dehydration, since all the water available in 

 the fish is required to excrete the protein metabolites. 

 A man might gain some water by drinking the juice 

 expressed from fish muscle, since this is largely free of 

 protein, but no one has yet been able to devise an ef- 

 fective method of doing this in a small boat at sea be- 

 cause the juices of the muscle are most tenaciously held. 

 Man simply cannot venture out upon the sea or into the 

 desert except in the security afforded by his providence. 



