2~> I'mf. R. Boyce. On the Study of /> r >,i(j [Mar. 15, 



the quadrigeminal region from the onter and dorsal part of the 

 crnsta. 



In the posterior commissure, pineal commissure, and corpus callosum 

 there are numerous degenerate fibres. 



When the motor area or anterior third of the brain is removed, the 

 degeneration is confined to the pyramidal system, the contrast with 

 the results of hemisection of the mesencephalon being, therefore, very 

 striking. 



Comparing hemisection of the mesencephalon with hemisection of 

 the cord, the difference, as regards the internuncial fibres, is the 

 greater amount of decussation in the mesencephalon than in the cord. 

 The internuncial fibres are conspicuous by their large size. 



Comparison with ascending degenerations at the various levels 

 shows that the descending tracts described above are distinct from 

 the ascending. 



Lesion of the Cerebellum. When one lobe of the cerebellum is 

 removed there is degeneration of the superior cerebellai peduncle. 

 I have found no evidence of the descending columnar degeneratic 

 described by Marchi. 



PART II. Symptoms of AnimaU during Life. 



Comparing the relationship between the extent of the degenera- 

 tions and the symptoms, it is found that 



Removal of the motor area entails degeneration of the pyramid 

 alone, and a temporary paresis ; the animal appearing, after a 

 short time, quite like the normal. 



Removal of a cerebral hemisphere or hemisection in the quadri- 

 geminal region gives rise to degeneration of the pyramidal and 

 intern uncial systems and fibres. The symptoms are more pro- 

 nounced; sensation is much altered; there is great difficulty of 

 feeding. 



Hemisection of the cervical spinal cord produces extensive degene- 

 ration of the anterior and lateral columns of the cord. There is 

 at first hemiplegia, the vasomotor disturbance is much greater, 

 and the sensory and motor paresis lasts longer. 



Removal of a lobe of the cerebellum does not appear to be accom- 

 panied by descending columnar degeneration ; the symptom* || 

 may be very slight, or there may be incoordination and sensory 

 and motor weakness upon the side of the lesion. The manifesta- 

 tion of the motor weakness differs from that seen in the cats, in 

 which the pyramid is degenerate. There is no wrist drop in the 

 cerebellar cat. The weakness in the case of the pyramidal cats 

 is uncomplicated ; on the contrary, that in the cerebellar cat is 

 intimately bound up with complex phenomena of incoordination. 



