A Study of some of the reactions of the Whelk, Buccinum 

 undatum. — By James Nelson Gowanloch, B. A., B. Sc, 

 Head of the Department of Zoology, Dalhousie Univer- 

 sity, Halifax, N. S. 



(Read by Title 11 May, 1925) 



The study of the reactions of animals to stimuli affords 

 an instructive method of analyzing the mechanism of those 

 organism-environment relations by means of which the living 

 animal apparently free to wander through a wide and vary- 

 ing range of conditions is nevertheless normally restricted to 

 those parts of its environment affording it appropriate condi- 

 tions of moisture or of aridity, of sunlight or of darkness and 

 of food. Properly controlled experiments on the response to 

 gradients of light, of hydrogen ion concentration or some such 

 chosen factor, provide a means of roughly measuring the direc- 

 tive value of these environmental elements whose aggregate 

 effects may constitute, in the absence of such analyses, a com- 

 plex and puzzling behaviouristic picture. 



There exist however in addition to these directive responses 

 on the part of the animal removed from its normal habitat a set 

 of what may be termed "protective responses" which operating 

 in an animal that has been displaced into a dangerous environ- 

 ment serve to reduce these dangers of its abnormal situation 

 and thus aid in tiding the organism over this hazardous period 

 of exposure. Such for example is the "clumping reaction" of 

 the land isopods Porcellio rathkei when removed to abnormally 

 dry surroundings, and such is the sealing up of the operculum 

 that is performed by gasteropods when they are exposed to 

 excessive loss of moisture. 



It is the purpose of this paper to set forth briefly the facts 

 of a case remarkable for the entire absence of these usual pro- 

 tective responses; an instance where in their stead a behaviour 

 occurs that not only increases greatly the physiological dangers 

 of the animal's situation but also actually causes the early 

 death of the exposed individual. The case is that of the Com- 

 mon Whelk Buccinum undatum L under conditions of inter-tidal 

 exposure. 



