182 ANIMAL BEHAVIOUR 



Miss Washburn (1909, p. 41) has inquired into the nature 

 of the Amoeba's mind, if haply it has one. There cannot be 

 more than three or four qualitatively different elements in 

 its experience; there is no evidence of memory images; it 

 probably has not more than flashes of consciousness. The 

 problem of the Amoeba's mind can wait, but it seems to us 

 clear that when we allow as much as possible to physical 

 properties (such as we see in the improvement of a violin 

 in the hands of a master), to the response of chemical bodies 

 to certain stimuli and no others (such as we see in photogra- 

 phy), to the purely physiological registration of experience 

 (such as we know in the improvement of well-exercised 

 muscles), there is a new aspect of reality appearing in the 

 behaviour of even an Amoeba. 



The slipper-animalcule, Paramecium, abundant in water 

 with decaying marsh plants in it, is a minute, cigar-shaped, 

 ciliated Infusorian, just visible to the naked eye as an 

 elongated whitish particle. Its rudimentary but very effec- 

 tive behaviour has been much studied, especially by Prof. 

 H. S. Jennings. One of the commonest episodes is that in 

 its swimming the Paramecium meets with something in- 

 jurious in the water, and exhibits what is called the " avoid- 

 ing reaction ". It reverses the action of its cilia and swims 

 away from the stimulus; at a certain distance it moves so 

 as to swing its anterior end in a circle, testing the water in 

 different directions ; when the sample from a certain direc- 

 tion no longer contains the obnoxious influence, the Para- 

 mecium goes ahead again in that direction, and may have 

 a free course till the next stimulus is experienced. When 

 the original stimulus is due to some mechanical obstacle, 

 Paramecium can get no hint from testing the water; it " tries 

 going ahead in various directions, till it finds one in which 



