BRACHIAL PLEXUS OF NERVES IN MAN 319 



There are 5 white female bodies with symmetrical arrange- 

 ment and 3 with asymmetrical, or 62.50 per cent symmetrical 

 and 37.50 asymmetrical among the 8 white females. In the 9 

 colored female bodies, there is a symmetrical arrangement and 

 in 6, or 60 per cent and in 40 per cent, an asymmetrical. This 

 gives a ratio of 3 to .2 among the colored females. 



A symmetrical arrangement was found most often among 

 colored males, least often among white males, and more often 

 among white than among colored females. The ratio of sym- 

 metry to asymmetry was in colored males 3 to 1, in colored 

 females, 3 to 2. Symmetry was 8.33 per cent more common than , 

 asymmetry in white males and 25 per cent more common in 

 w^hite females. 



Symmetry as, regards the type of plexus 



Among the 63 bodies where I have satisfactory records from 

 both sides of the body there are only 4 in which the type A 

 plexuses are found. All are asymmetrical. In two of them type 

 A is on the right side, 1 white male and 1 white female. In two, 

 type A is on the left, both in colored females. It is interesting 

 to note that in both the cases where the B type of plexus is on 

 the right side there is a lateral head to the ulnar nerve on this 

 side. In the cases where the B type is on the left side, there is 

 no such branch. 



There are 76 plexuses of the B type and in 54 of these it oc- 

 curred on both sides of the body, or in 71.05 per cent. In the 

 22 bodies in which the B type is found only on one side, the A 

 type is found on the other side in 4, 2 right and 2 left, type C 

 is on the left in 2, the E type is on the left in 7 and on the right 

 in 6, and the F type on the left in 3. It will be noted then that 

 in 14 of the above the B type is on the right and in 8 on the left 

 or nearly 2 to 1. 



There are 2 records of C type plexus both on the left side of 

 white malfes and the type B plexus is on the right. 



There is but one record of type D. This is on the left of a 

 white male and the type E plexus is on the right. 



