20 F. T. ROGERS 



The writer has been accustomed to leave a bridge of bone over- 

 lying the longitudinal sinus and then cutting through the dura, 

 parallel to the median sulcus and to the occipital pole of the 

 hemisphere. Hemorrhage from the large superficial artery run- 

 ning over the anterior surface of the hemisphere may be con- 

 trolled with a cautery and the entire hemisphere removed with 

 a blunt probe whose tip has been curved to fit around the posterior 

 end of the hemisphere. This can be removed, the hemorrhage 

 controlled with cotton, and a clear view of the thalamus and the 

 third ventricle obtained. The writer has then destroyed the thala- 

 mus either by excision or by the use of a hot cautery. The lat- 

 ter is more satisfactory, in that it controls bleeding as well as 

 destroying the thalamus. 



In the second place, it has never been found satisfactory to 

 leave cotton or any packing in the cranial cavity, but to allow 

 the cavity to fill itself with blood and sewing the skin over the 

 cavity. No attempt was made to approximate the cut edges 

 of the dura, because of its delicacy and the fact that traction on 

 the dura may increase the hemorrhage. 



After the most careful operative work it is found that only one- 

 fourth to one-third of the animals will live for more than a few 

 days. These early fatalities seem to be due to circulatory dis- 

 turbances. The percentage of survivals can be increased mark- 

 edly if the thin medial and occipital cortex is not removed. These 

 parts are so closely related anatomically to the large blood-ves- 

 sels of the brain stem that their removal is particularly likely to 

 be associated with excessive bleeding. 



EXPERIMENTAL RESULTS 



Complete removal of all forebrain substance anterior to the 

 thalamus gives a preparation which, if the animal lives over the 

 initial shock, conforms to the classic description. Certain fea- 

 tures are characteristic of such an animal: 



1 . The bird stands quietly on one or both feet most of the 

 time. 



2. The feathers are fluffed as in the sleeping condition. 



