Secondary Degeneration follovvin^ti; Unilateral Lesions etc. 331 



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partial section of the coi'd, iisiiig the Marchi method, found iibies ]jas- 

 sing from the crossed pyramidal tract into the base of the posterior 

 horn while none could be traced to the anterior horn. The corre- 

 sponding- fibres which I have obsei'ved in the cervical and lumbar en- 

 largements were most evident in the monkej^ but a few could be made 

 out in the cat. They appear not to be so abundant when the lesion 

 is a cortical one as when the cord is hemisected so that in the lat- 

 ter case they may come from more than one source. 



In conclusion I would desire to call attention to the following 

 which I consider to be the main points brought out in the course of 

 my investigations: — 



1. In the cat, fibres pass freely from the crusta to the grey 

 matter of the anterior corpus quadrigeminum of the same side in which 

 for the most part they appear to end, a few crossing the middle line 

 in the roof of the aqueduct to terminate in that of the opposite side. 



2. In all the animals examined (cat, dog, monkey) extensive fine 

 degeneration is present in the grey matter of the nuclei pontis on the 

 same side as the cortical lesion, indicating an important cell-station 

 in relation to the pyramidal tract in this region (pons Varolii). 



3. No fibres are seen to pass to any of the cranial motor nuc- 

 lei, or to the ventral horn of the spinal cord, but a few can be 

 traced into the grey matter of the spinal cord at the base of the 

 posterior horn. 



4. A possible explanation of the fibres seen in the upper half of 

 the medulla oblongata leaving the degenerated pyramid and passing 

 to the formatio reticularis of the same and of the opposite side, may 

 be that they belong to the spinal motor decussation and are destined 

 for the lateral columns of the cord. These fibres may correspond to 

 what has been described as Pick's bundle in the human subject. 



The drawings were done by Mr. Richard Muir of the Pathological 

 Department of this University and I would take this opportunity 

 of thanking him for the care and accui'acy with which he has exe- 

 cuted them. 



