5G Wisconsin Academy of Sciences^ Arts and Letters. 



The table shows that considerable individual differences 

 are present. In No, 36 the 8th nerve has twice as many 

 fibres as the 9th. In No. 42 the relation is reversed. Usu- 

 ally the 6th nerve is larger than the 5th, but occasionally the 

 otli is the larger, etc. The relations are more regular when 

 groups of nerves are considered. If we neglect the contri- 

 bution of the 1st nerve to the brachial plexus and that of the 

 10th nerve to the lumbar plexus, we have: 



TABLE VI. 



The brachial plexus contains at least as many fibres as the 

 lumbar, and the relative size would be still more striking 

 if the parts of the 1st and 10th nerves were assigned to their 

 respective places. 



The variation in individual nerves appears most plainly in 

 the hinder half of the cord, and is very probably due to the 

 relation of points of exit of nerve from cord and spinal 

 column. When a nerve fibre has considerable distance to 

 travel before leaving the spinal canal, it makes little differ- 

 ence whether it leaves the cord in one or another root. It is 

 only necessary that it gain the proper nerve-trunk and this 

 ^s determined by the plexus. 



II. The Motor Ganglion Cells op the Spinal Cokd. 



The cords whose cells were to be counted were stained in 

 Grenadier's alum carmine, imbedded in paraffino, and the 

 sections cut of a uniform thickness, usually 1-50 mm. They 

 were mounted in order and covered with xylol balsam. 

 In this method the nerve fibres are little stai ned, while nu- 

 merous granules and ganglion cells are tinged with a more 

 or less deep red. In the anterior horn of the gray matter 

 lies the group of closely-joined, large motor cells whose 

 number is to be determined. The only difficulty in counting 



