135 
Somewhat ambiguous cases are represented by the variety 
illustrated in Fig. II. In some instances the association was closer 
than that figured. But the type chosen was one in which the con- 
nection with the sympathetic might easily be overlooked had it not 
been specially searched for. I therefore had sections cut in this type 
at the points A, B, C, D, E, and F, that I might study the character 
of the individual fibres. As a result I found that the communi- 
cation F contained some large medullated fibres but the majority 
of the nerve was composed of small medullated and non-medullated 

Fig. 3. Microphotograph of the communication from the 2nd to the Ist 
dorsal nerve (F' in Fig. 2). 
Note some large medullated fibres and many small medullated and non- 
medullated fibres. 
Fig. 4. Transverse Section of first dorsal nerve for comparison with Fig. 3. 
Note the great majority of the fibres are of the large medullated variety. 
fibres (see Fig. III). I was therefore correct in concluding from 
the naked eye dissection that sympathetic fibres may in some 
instances enter largely into the constitution of thecommunication 
between the first and second dorsal nerves. 
I have drawn attention to the clinical significance of this sym- 
pathetic connection of the brachial plexus in a recent paper in the 
Lancet. 
The vascular symptoms of “ cervical”’ rib are pressure pheno- 
mena, as are the nervous symptoms. They are caused by physiological 
separation of the sympathetic fibres from their central connections (17). 
Since that article went to the press I find that KEITH has made 
the same suggestion (18). The physiological severance of vascular 

