Some Simple Experiments in Animal Behavior 



W. C. Allee. 



It is possible to illustrate the essential reactions of the lower 

 animals in a simple manner and without expensive apparatus. 

 The experiments here suggested will mainly involve crustaceans 

 since their habitats and the methods of collecting them have been 

 recently discussed in this magazine.^ In general they can be 

 worked with any small water animal and, with the obviously 

 necessary adjustments, with any small land inhabiting animal 

 as well. 



In animal behavior the response of the organisms to a given 

 stimulus is spoken of as a tactic response. In general, this means 

 that the organisms react to the given stimulus in a more or less 

 definite manner, but it expresses nothing regarding the presence 

 or lack of orientation, the speed of the reaction or the detailed 

 behavior by which the response is brought about. The names 

 of a number of the tactic responses together with the stimuli 

 causing them are as follows : 



Reaction Stimulus 



Phototaxis Light 



Thigmotaxis Touch 



Thermotaxis Temperature 



Rheotaxis Current of water or air 



Geotaxis Gravity acting as a stimulus 



Chemotaxis Chemical 



Electrotaxis Electricity 



In all of these, the reaction is positive if the animal goes toward 

 the source of the stimulus ; if in the reverse direction, it is negative. 

 If on the other hand the animal reacts to the stimulus but does not 

 move in a definite manner as regards the stimulus, it must be 

 classed as giving an indefinite reaction. ^ 



In animal behavior, there is one golden rule of experimenta- 

 tion; that is, to vary one factor at a time, and only one. In 

 order to test whether more than the factor under experimentation 

 is varied, it is necessary to run a control experiment. Everything 

 in the experiment and the control are to be exactly the same as 

 far as can be told except for the one factor under experimentation. 



^Allee, Nature-Study Review, Vol. 9 No. 4. 



^For a more complete discussion of these fundamentals of animal behavior 

 see Holmes, The Evolution of Animal Intelligence. Henry Holt & Co. 296 pp. 

 1911. 



