BY JAMES NELSON GOWANLOCH 135 



were recovered, eleven of which were dead. Since it was evi- 

 dent that their death was in no way due to experimental treat- 

 ment, an examination of the normal, unm.arked Buccinum 

 present at this level was immediately made with the surprising 

 result that it was found that nine-tenths of these animals were 

 also dead. The explanation of this heavy mortality must lie, 

 it was thought, in some unusual failure of Buccinum to conserve 

 its water-content during exsiccation and an experimental exa- 

 mination of the animal's behaviour during intertidal exposure 

 was undertaken accordingly. 



Ten Buccinum ranging in weight from 8.25 grams to 41.17 

 grams were weighed and exposed in a dry paraffined tray sus- 

 pended over a water table which was covered with flowing sea- 

 water. These conditions thus reproduced very accurately 

 those under which the animals would be exposed in nature 

 during low water of a spring tide on a cloudy day. The animals 

 were then weighed at intervals during the twenty-one hours 

 and forty-five minutes that elapsed from the beginning of the 

 period of exposure until the time when all the animals had died, 

 there being seven successive weighings for each individual. The 

 animals were then desiccated for three days in a drying oven 

 and weighed again and subsequently a chosen group were mac- 

 erated, the tissues other than the shell removed, the shells being 

 again desiccated and weighed. From these data there was then 

 calculated the rate of loss of water per hour in percentages of the 

 initial total water content providing thus in exact terms the 

 record of each individual's approach to the point where loss of 

 water caused death. During the experiment the activities 

 of the animals were constantly observed. The results may be 

 concisely summarized as follows. When Buccinum is subjected 

 to exsiccation it responds in a manner precisely the opposite 

 from that exhibited by a gastropod such asLitiorina litorea, a form 

 occurring regularly far up into the zone of inter-tidal exposure. 

 Instead of withdrawing into its shell and sealing up its operculum 

 as does Littorina, Buccinum promptly extrudes its foot and 

 head, exposes" almost the maximum possible surface to the 

 action of evaporation and, most disastrous of all, violently 



