162 



Mr. J. G. Wilson. 



[Jan. 21, 



might be tempted to acquiesce in the above view, at any rate provisionally. 

 But the work since then, especially of Buffini(ll) and Sherrington (12), 

 has so widened our knowledge of the neuro-muscular spindle that Golgi's 

 definition is now inadequate, and it is with the complex nerve ending which 

 they describe that the atrio-ventricular bundle must be compared. 



The essential anatomical points in the structure of the neuro-muscular 

 spindle may be summed up as follows : — 



(1) The fibres which go to form the muscle bundle (Weissmann's bundle) 

 in the neuro-muscular spindle have a diameter less than that of the ordinary 

 muscle fibre. The fibres are directly in apposition, and no connective 

 tissue lies between them, though connective tissue lies around Weissmann's 

 bundle and constitutes the axial sheath of Sherrington. The striatum of the 

 fibre is usually only marked in the marginal area, and so on transverse 

 section it looks like a Purkinje fibre. Begarding the two ends of Weiss- 

 mann's bundle, one, the wider end, is muscular ; the other tendinous where 

 the axial fibres of the bundle are attached to the fibrous tissue of the 

 capsule or to the tendon of the muscle. 



(2) Around it lies a lymphatic space. 



(3) There is a distinct capsule of concentric superposed lamellae of con- 

 nective tissue. At the tendinous end of the muscle bundle it is thin and 

 adheres to the tendinous portion of the spindle ; at the muscular end it is 

 thin and may be absent. 



(4) In the vast majority of cases it is fusiform in shape. 



Contrast this with the anatomical description given of the atrio-ventricular 

 bundle in this paper, and it will be seen that, apart from the muscle cells being 

 similar to Purkinje fibres, they have nothing in common. This lack of agree- 

 ment is further emphasised when we compare the nerve constituents of each : — 



(5) To the distribution and termination of the nerves in the neuro- 

 muscular spindle, with its three distinct kinds of endings described by 

 Buffini, there is nothing comparable in the atrio-ventricular bundle. 



(6) Ganglion cells are not present in the neuro-muscular spindle, whereas 

 they are a marked feature in the atrio-ventricular bundle. 



•Prom the above, one must conclude that, whatever the physiological 

 significance of this bundle may be, it has anatomically nothing in common 

 with the neuro-muscular spindle. 



In conclusion, I wish to express my great indebtedness to Dr. Mott for 

 allowing me to carry out a considerable part of this investigation at the 

 Pathological Laboratory at Olaybury, and for his kindness in assisting me 

 to procure a large part of the material which has been used. 



