218 Dr.Beale Croonian Lecture. [May 11, 



that they could be beneath the sarcolemma, while in many cases the outline 

 of the sarcolemma can be followed underneath them. Secondly, it appears 

 probable that they are a reduplication and expansion of continuous fibres, 

 rather than terminal organs formed upon the extremities of the nerve-fibres ; 

 nor would it seem that these organs are essential to the action of nerves 

 upon muscle, since they are only to be demonstrated in the muscles of cer- 

 tain animals. Moreover, as many different forms of these nerve-organs are 

 to be seen in a small piece of muscle, exhibiting different degrees of com- 

 plexity, we may perhaps by studying them attentively be able to draw a 

 true inference as to their real structure and the mode of their formation. 



Kuhne's idea of the structure of these bodies is represented in this 

 diagram, which has been copied from his last paper. The interpretation 

 of the appearances here given is totally different from that which I have been 

 led to offer. In my specimens the nerve-fibres entering into the formation 

 of these tufts are seen to divide and subdivide into several branches, which 

 are folded, as it were, upon one another. The fibre in many instances does 

 not consist of the axis-cylinder only, but the white substance may also be 

 detected in connexion with some of the fibres. The nuclei seem to be con- 

 nected with the finer branches of the nerve-fibres. In fact the organ seems 

 to consist partly of broad fibres, partly of fine fibres formed by the branch- 

 ing, spreading out, and coiling of the fibres resulting from the subdivision 

 of the original nerve-fibres which enter into the formation of the tuft. 

 Moreover I have succeeded in demonstrating that, from various points of the 

 oval coil, branches pass off and run on the surface of the sarcolemma, pro- 

 bably passing on to other nerve-bundles. These fine fibres, which are 

 represented in my drawings, have not been delineated, as far as I am aware, 

 by any previous observer who has examined these bodies. In connexion 

 with every nerve-tuft there seem to be entering and emerging fibres ; and in 

 the majority of instances, fine fibres may be traced from the tuft in several 

 different directions. 



When the nerve-tuft is formed, as it were, upon the trunk of the fibre, the 

 entering fibres are more numerous and larger than the emerging fibres. 

 This is probably to be explained by the circumstance that some fibres pass 

 away from each tuft upon the surface of the muscle, and thus establish 

 communications with nerve-fibres which approach the elementary mus- 

 cular fibre at other points. This drawing explains how, as the muscular 

 fibre grows, the bundles marked a and b become separated further and 

 further from one another, and the fine communicating fibres connecting 

 them necessarily become so very much drawn out that they are too delicate 

 to be seen upon the surface of the sarcolemma. 



And now it must be obvious that these bodies precisely correspond to the 

 bendings and division of the fine dark-bordered fibres at the point where 

 they come into contact with the surface of the sarcolemma, in the breast- 

 and other muscles of the frog. At this point there is always a twisting of 

 fibres with free branching, and the formation of a number of exceedingly 



