492 A MANUAL OF VETERINARY PHYSIOLOGY 



but that it was an organ containing within itself other organs 

 functionally distinct, yet intimately connected, was never 

 anticipated. 



We have seen that the decerebrated frog is a reflex machine, 

 but with animals so low in the scale it is difficult to obtain 

 any real knowledge of the function of the organ. 



Removal of the Cerebrum. — The pigeon with the cerebrum 

 removed becomes converted into a drowsy, lethargic animal, 

 unable to feed itself, though it may try in an aimless manner 

 to do so. It can fly and perch, may be wakened by a loud noise, 

 shows no fear, and is not possessed of a maternal feeling. It may 

 awake sufficiently to preen itself, gape, and then once more 

 returns to its condition of somnolence. So far as can be 

 judged, the chief loss this animal has experienced is that of 

 memory. 



Colin removed the cerebra in horses. He notes that the 

 animal fell almost before the superficial layer had been taken 

 away. The horse so dealt with was unaffected by stimulation, 

 gave no indication of feeling pain, noises were not heard, light 

 had no effect upon the pupil, and there was no eyelid reflex. 

 Ammonia applied to the nostrils caused no irritation, and taste 

 and all special senses were lost. In the decerebrated heifer the 

 animal was able to stand, but could not see ; hay was held in the 

 mouth and not masticated,* and no notice was taken of the 

 blowing of a horn. 



If partial destruction of one hemisphere in the horse be prac- 

 tised, the animal may be kept on its legs for a short time. The 

 superficial layer of the right cerebral lobe was removed in the ass, 

 and the animal remained standing for nearly an hour. The 

 limbs on that side were slightly bent under the influence of the 

 body weight, and the animal moved with difficulty, and, if left 

 to himself, remained immobile. When made to walk he walked 

 very quickly, now and then in a circle in the direction opposite 

 to the lesion. If he walked into anything, he fell, but could be 

 raised. In another ass the left hemisphere was incised in the 

 direction of its length, and immediately hemiplegia occurred 

 on the right side ; the animal fell on that side, and could not be 

 got up again. In many horses a puncture through the entire 

 thickness of the cerebral lobes sometimes sufficed to cause the 

 animal to fall and to be unable to rise. Bo vines withstood far 

 better than equines mutilation of the cerebral lobes. A heifer 

 with one cerebral lobe removed remained standing for more than 

 half an hour, retained its vivacity, and walked with such ease 

 that it was extremely difficult to observe the muscular deficiency 

 on the opposite side to the lesion. When the remaining lobe was 

 * A common symptom in the horse suffering from brain trouble. 



