478 E. V. Cowdry. 



imbedded, sectioned, and stained according- to Heidenliain's (1906) iron 

 liematoxjdin method. The results were very satisfactory (fig. 2); for 

 in those fixed four 22 hours in a cold saturated solution of potassium 

 bichromate, stained with iron hematoxylin, and counterstained in a 

 l^/o aqueous solution of erythrosin, fine dark gray or black rods, 

 similar in all respects to those seen in .the Altmann preparations, 

 could be observed. It seems evident from a consideration of Held 

 1897a, plate III, fig. 10, that these bodies are the neurosomes seen 

 by him. 



The arguments in favour of the identity of the neurosomes which 

 Held observed in his Altmann and iron hematoxylin pi-eparations are: 



1. Similarity in relative number, size, shape (rod-like), clearness 

 of outlines, uniformity of staining affinities, distribution and orientation 

 in the cytoplasm. 



2. The iron hematoxylin technique was employed by Held after 

 potassium bichromate fixations, but it demonstrates these bodies clearly 

 after Altmann fixation, and the Altmann staining method after fixation 

 in potassium bichromate. That is, the methods of staining are inter- 

 changeable, there being no difference in the staining reactions of the 

 neurosomes as demonstrated by the ii'on hematoxylin and Altmann 

 methods used by Held. 



The evidence for the conclusion that the granules, which he 

 studied by means of his erythrosin-methylene blue technique after Alt- 

 mann and other fixations, are of a different nature is a follows: 



1. They are more numerous than are the bodies demonstrated by 

 the Altmann and iron hematoxylin methods, especially in the region 

 of the axone hillock where they are densely crowded together. 



2. Their size is variable, ranging from the most minute specks 

 to fair sized granules; and their shape is extremely irregular. Con- 

 trast this with the uniformly rounded, rod-like neurosomes just men- 

 tioned. 



3. The staining reactions of these bodies are also variable, some 

 staining with greater intensity than others. 



4. Supplementary evidence is derived from the fact that these 

 bodies, demonstrable by the erythrosin-methylene blue method, cannot 



