482 THE BRAIN. 



Fig. 159. 



THE "AZTEC" IDIOTIC CHILDREN. Taken from life, at five and seven years of age. 



articulate language, and, as in other idiots, mental instruction was with- 

 out result. 



III. Experiments performed upon the lower animals, by removal of 

 the hemispheres, lead to a similar result. In large and full grown mam- 

 malians the injury is usually fatal, owing in* great measure to the. 

 attendant hemorrhage ; but it may be performed in fish, reptiles, birds, 

 and sometimes in young quadrupeds without producing death. Vulpian 

 has succeeded in maintaining life, after this operation, in the frog, the 

 turtle, the pigeon, the cock, the rabbit, and the rat. The result is that 

 these animals retain their sensibility and power of motion, and continue 

 to maintain the normal attitude and to perform many instinctive and 

 reflex movements ; but spontaneous action, and its conscious adaptation 

 to external conditions, is abolished with the removal of the cerebral 

 hemispheres. 



The operation is very readily performed upon the pigeon, and its 

 effects in this animal are uniform and distinctly marked. After removal 

 of both hemispheres, the bird maintains without difficulty the standing 

 posture, and will even rest upon a perch with security if undisturbed ; 

 but he remains in a state of profound quietude, almost completely indif- 

 ferent to surrounding objects. He stands upon the ground or rests 

 upon his perch, with the eyes closed and the head sunk between the 

 shoulders. The plumage is smooth and glossy, but is uniformly ex- 

 panded, by erection of the feathers, so that the body appears puffed out 

 and larger than natural. Occasionally the bird opens his eyes, stretches 

 his neck, shakes his bill once or twice, or smooths down the feathers 

 upon his shoulders, and then relapses into his former apathetic condi- 

 tion. This characteristic state of immobility comes on immediately after 

 removal of the hemispheres. 



It is not accompanied, however, by loss of either general or special 

 sensibility. If the foot of the bird be pinched with a pair of forceps, he 

 becomes partially roused and moves uneasily once or twice from side to 

 side, as if to escape the irritation. Yulpian has seen a pigeon within a 



