36 H. V. NEAL 



Thus Paton not only doubts the neuroblastic origin of the 

 connections between the tube and myotome but also the neu- 

 roblastic origin of the neuro-fibrillae. That he has been led into 

 error in his inference of the independent origin of the neuro- 

 fibrils will be suggested by a comparison of Paton's figure 2 

 with figure 12 of this paper. Paton is mistaken in his inference, 

 partly because of his failure to trace carefully in earlier stages the 

 genesis of the protoplasmic bridges; partly because he has not 

 used a method suitable to demonstrate cell boundaries, and part- 

 ly because the neuro-fibrillae in his preparations are incompletely 

 stained, as has already been stated by Held ('09). A compari- 

 son of Paton's figure 2 with figure 12 of this paper shows that the 

 'primitive fibril' which Paton thinks arises within the myotome 

 actually lies between the myotome and the sclerotome. More- 

 over, its position corresponds with the position of the termination 

 of the cell processes of medullary cells. The two drawings strik- 

 ingly show the difference in the histological results of the \-om 

 Rath and the Bielchowsky-Paton methods. The great advantage 

 of the former appears in the sharp definition of the cell bound- 

 aries, of the latter in the clear differentiation of the neurofi- 

 brils. The convincing proof given by Held ('09) of the endog- 

 enous origin of the neurofibrils within medullary neuroblasts 

 certainly warrants the inference that the neurofibrils are in- 

 completely stained by the Bielchowsky-Paton method. Later 

 in his paper Paton admits the possibility that the neurofibrils 

 are genetically related to the processes of the medullary cells. 

 But he thinks that new technical methods are needed in order to 

 solve the problem thus raised. To determine this, however, 

 needs not so much a new method of neurological technique as 

 a careful study of the successive stages in their differentiation 

 by methods which we now possess, especially a method like the 

 vom Rath which defines clearly the cell boundaries and relations. 

 Paton's procedure admirably supplements such a method. 



Held ( '06, '09) has made a most thorough and painstaking 

 investigation of the histogenesis of the neurofibrils on the ground 

 that, as stated by Max Schultze, von Kupffer and von Apathy, 

 these are the distinctive structures of the nerve fiber. In agree- 



