MENTAL PHENOMENA IN ACEPHALOUS ANIMALS. 5 



experiment (QuaJcversuch) in the frog, after the cere- 

 bral hemispheres have been removed, gentle stroking of 

 certain parts of the body, by means of the finger or any 

 broad smooth surface, produces a croak of satisfaction, c once 

 at each stroke, with machinelike regularity ; ' but if the 

 animals are ( touched or stroked with a sharp instrument, 

 they do not croak, but execute defensive movements. . . . 

 When any nerve-trunk is irritated they sometimes utter a 

 sound indeed, but it is the cry of pain and never the croak 

 of contentment ' (Brunton) . 



2. According to Magendie, Longet, Flourens, and Schiff, 

 a pigeon with its cerebral hemispheres removed, if thrown 

 into the air, flies ; if laid prone, gets up ; shuts its eyes in 

 a bright light ; preens its ruffled feathers ; follows with its 

 head the movements of a candle ; stands on one leg and then 

 changes to the other, maintaining its balance or equili- 

 brium ; shakes its head and puts it under its wing for sleep 

 in other words, it receives and responds to certain kinds of 

 external as well as internal impressions. 



3. In Ppfliiger's well-known vinegar experiment on decapi- 

 tated frogs, if a drop of acetic acid be applied to one thigh 

 the animal wipes it off, or endeavours to do so, with the op- 

 posite foot or leg ; the animal, in short, makes experimental 

 efforts to expunge the irritant, while its legs also 'make 

 efforts to push away the probe with which its cloaca is being 

 irritated' (Carpenter). 



4. Suction of the mother's teats by the brainless puppy 

 (Grainger). 



5. The decapitated salamander swims (Dumeril). 



6. The brainless rat, if a sharp noise be made, bounds 

 away as if alarmed (Yulpian). 



7. The anencephalic infant not only moves its limbs, but 

 sucks and cries. 



Similar actions are performed by animals that have been 

 not only decapitated, but dismembered or cut into sections. 

 Thus the segments of a myriapod walk the capital seg- 

 ment avoiding obstacles in the absence of vision (Hou- 

 zeau) . 



Now, these actions involve the following phenomena : 



