544 



7 HE AM ERIC AX NA TL 'R A LIST. [Vol. XXXV 1 1 . 



Bethe's methods for neurofibrils. Preparations were also made 

 by the cover-glass method for blood technique. This is well 

 adapted for experiment in- with a large number of reagents and 

 stains, and has the advantage of insuring immediate fixation. 



The examination of material prepared in the ways enumerated 

 gave evidence of a well marked axial core in the outer segment 

 of each rod. This core was seen in both longitudinal and 



mentioned and measured about one fourth the diameter of the 

 rod. It took none of the stains which I have tried with the 

 possible exception of picric acid. It is probably the structure 

 long ago seen by Dreser ('86) and recently identified by Bernard 

 (:oi, p. 465) as the condensed reticular portion in the axis of 

 the rod. Its relative thickness precludes the possibility of its 

 being the so-called fibre of Ritter, if in fact this fibre exists. 

 At present I do not wish to express any opinion as to the exact 

 nature of this core. 



As previously stated the substance of the rods has been 

 variously described as lamellar, spirally fibrous, etc. Since rods 

 prepared by different methods showed much difference in 

 structure, it was necessary to study fresh ones as a means of 



under the ordinal}- nucn»e<>pe the substance of fresh rods 



ized light seemed the most likely means, for, if the rods are 

 fibrous not only ought this to be open to determination by a 

 polarizing microscope, but it ought also to be possible by the same 



