270 Prof. R. Boyce. On the Study of Descending [Mar. 15, 



Where the animals have been kept alive, tlje symptoms during life 

 and the anatomical changes found after death have been investigated, 

 and in all cases the results of absinthe stimulation have been recorded 

 by the graphic method. 



In order to enable a clearer comparison to be made between the 

 various results obtained by the experimental and anatomical methods, 

 the paper is divided into 



I. The anatomical changes. 

 II. Behaviour of the animal during life. 



III. Results of absinthe stimulation. 



IV. Conclusions. 



PART I. Anatomical Changes. 



The investigations of the degenerations have been made in evt 

 instance by the Marchi method upon animals which have been kef 

 alive from a few days to three months. 



Removal of one Cerebral Hemisphere (Left), or complete Section of the 

 Left Cms Cerebri flush with the Tentorium. 



The results of these lesions as regards the descending degenerations 

 are identical. 



They show that in the higher bulbo-spinal segments, from the 

 3rd nerve downwards, there exist long descending internuncial fibres, 

 which are grouped anteriorly and laterally as in the spinal cord ; in 

 other words, that the anterior, antero-lateral, and lateral columns of 

 the cord can be traced from the level of the superior corpora quadri- 

 gemma. 



Anterior Columnar Fibres. These fibres begin to group at the level 

 of the uppermost part of the 3rd nerve against the anterior and inner 

 aspect of the grey matter of the aqueduct of Sylvius ; they constitute 

 the commencement of the posterior-longitudinal bundle. The degener- 

 ate fibres are absolutely limited to the side of the lesion; they occupy, 

 for the most part, the inner portion of the posterior-longitudinal 

 bundle, and they can be traced to the end of the cervical spinal cord. 

 The higher the lesion the fewer are the number of degenerate fibres in 

 the post. -longitudinal bundles ; if the lesion extends much below the 

 3rd nerve, the degeneration of the post.-longitudinal bundle is very 

 complete. New fibres are continually being added to the post-longi- 

 tudinal bundle in its passage through the bulbar segments, the 

 degenerate fibres in consequence moving more anteriorly. In the 

 spinal cord the degenerate fibres are scattered through the middle 

 and post.-thirds of the anterior column on its inner aspect and closely 

 simulate a direct pyramidal tract. 



