Edinger, The Significance of the Cortex. yi 



in the region of the corpora quadrigemina only sHght divergence 

 from the normal conditions are observable at first sight. 



In this section of spinal cord you will detect nothing to dis- 

 tinguish it from a section from a normal dog, and it is only after 

 close inspection that you will discover that a few fibres are ab- 

 sent from dorso-lateral columns and that the whole pyramidal 

 tract, which is not very strongly developed in the dog at best, 

 is affected by secondary degeneration on both sides. Even in 

 these sections of the medulla and quadrigemina no one would 

 discover without careful study that farther forward such an 

 enormous region of the ventral nervous system had been in- 

 jured. Erom these observations we might conclude that the 

 spinal cord and the ganglia and fibres in the medulla and mid- 

 brain are distinct centres which possess a high degree of ana- 

 tomical independence of those parts of the brain lying farther 

 cephalad. The functions which they subserve, motor co-ordi- 

 nation, receptivity to sense impressions, were not so ser- 

 iously affected in this dog. The opinion which might be 

 formed on anatomical grounds, that an animal which retains only 

 these centres intact could, in case of necessity, get on with them 

 alone, has become certainty through the evidence afforded by 

 eighteen months' observation of this dog. I shall discuss this 

 point more in detail later. 



Glance, in the next place, at the illustrations of sections 

 through the forebrain. These were prepared by drawing the 

 outline of the sections through the fragments of brain of the op- 

 erated dog and projecting sections from the same level of normal 

 dog brains. The projection distance was so adjusted that the 

 two outlines were made to correspond and thus articial figures 

 of two equal brains were produced. 



It appears that almost the entire forebrain has been re- 

 moved in an extraordinarily skiltul and complete manner. 

 Cephalad both the frontal lobes are absent, together with a part 

 of the striatum and the callosum and corpus fornicis. On the 

 right side a part of the internal capsule is retained with the 

 body of the striatum but on the left side only traces of these re- 



