322 S. Simpson, 



homolateral fibres than in the cervical reg-ion. At the 4^^ lumbar 

 segment a few fibres can be traced from the degenerated pyramidal 

 tract into the grey matter at the base of the posterior horn, and in 

 this grey matter there is a small amount of fine degeneration. From 

 ten to twenty homolateral degenerated fibres are visible on the left 

 side (fig. 16. pi. XVII). A section passing through the 4*^ sacral segment 

 (fig, 17. pi. XVII) contains 25 crossed (heterolateral) and 4 or 5 un- 

 crossed (homolateral) pyramidal fibres. There is no evidence of a 

 direct (anterior) pyramidal tract anywhere in the spinal cord. 



Case IL Macacus Rhœsus. Male. Lesion. The whole of the 

 left motor area was "under-cut" as in the last case and by a similar 

 operation. 



Symptoms. Following the operation there was conjugate devia- 

 tion of the head and eyes to the left which disappeared after the first 

 day. There was right-sided motor and sensory (tactile) paralysis and 

 right homonymous hemianopsia. (I have no record as to how long 

 these symptoms lasted.) The animal was killed 16 days after the 

 operation. 



Secondary Degeneration. In the mid-brain the left crusta is de- 

 generated in its middle '^ö*^^ the mesial and lateral portions being 

 free, but no fibres can be traced into the tegmentum as in the case 

 of most of the cats examined. There is a considerable amount of fine 

 degeneration in the substantia nigra of the same side. In tlie pons 

 there is fine degeneration in the region of the nuclei pontis around 

 the degenerate pyramidal bundles on the left side. Sections through 

 the different levels of bulb and spinal cord closely correspond to those 

 already described in Monkey I. This was the first material which I 

 had stained by the Marchi method, and in sections of all the regions 

 below the mid-brain there was a general precipitation throughout, due 

 to faulty technique, but this can be easily distinguished from the de- 

 generation. 



In all the cases (cats, dog and monkeys) the degenerated pyra- 

 midal tract was atrophied and appeared distinctly smaller to the 

 naked eye than tlie normal tract on the opposite side. Nowhere was 



