I/O Journal of Comparative Neurology. 



most clearly the shape and arrangement of the ultimate branches 

 of the axis cylinder; there exist however differences of opinion 

 as to the relation of such endings to the muscle fiber or muscle 

 cell, its sarcolemma, muscle substance and muscle nuclei. This, 

 we believe, is largely due to the fact that such observations 

 have been made on methylene blue stained tissues fixed in am- 

 monium picrate and cleared in glycerine. Tissues prepared by 

 this method are usually examined in relatively large pieces or 

 in teased preparations and, while many important observations 

 may be made on such preparations, as the results of Dogiel and 

 Retzius may show, the observer is often left in doubt concern- 

 ing this or that point of interest. 



It occurred to us that by using the intra vitam methylene 

 blue method of Ehrlich as improved by Bethe, where the 

 stained tissues are fixed in ammonium molybdate, and may 

 then be embedded in paraffin, sectioned and double stained, it 

 would be possible to obfain surface views, longitudinal and cross 

 sections of the motor endings in relatively thin sections, so 

 stained that the nerve and its terminal apparatus would be blue 

 and all other structures red. Such preparations, we hoped, 

 would throw new light on some of the disputed points and con- 

 firm facts more or less clearly established. We trust the facts 

 to be presented may substantiate our expectations. 



It was our wish to make the investigation more compre- 

 hensive, especially that portion which pertains to the motor 

 endings in striped muscle and heart muscle, but other duties 

 have interfered. It is thought however that enough observa- 

 tions are at hand to admit of drawing some general conclusions, 

 and further, that this exposition of the results obtained with 

 this method, may stimulate others to its use in similar inves- 

 tigations. 



The material was obtained as follows : 

 Motor endings : 



a. striped muscle, rabbit and frog (Rana halecina); 



b. heart muscle, cat ; 



c. involuntary muscle, cat, tortoise (Chelydra ser- 



pentina), and frog (Rana halecina). 



