62 'Journal of Comparative Neurology and Psychology. 



these bodies may vary in size, in number and in capacity for taking 

 up various staining agents. 



Nansen ('87) described the structure of the nerve cells of Patella vulgata, 

 Nereis, Lumbricus, Homarus vulgaris, Nephropa norwegicus and six different 

 Ascidians which he classed with the above. He found in the cells of the Nereidae 

 structures which correspond very closely in description to the granules commonly 

 known as Nissl bodies. Some of the granules were very large and prominent 

 and were situated in the mesial part of the protoplasm. In preparations fixed with 

 osmic acid and stained with haemotoxylin they were very dark, almost black in 

 color, and consisted of a fatty (myeloid .?) substance (Fig. 9). 



Fig. 9. 



Fig. 10. 



Fig. 9. The yellow granules are scattered tlirough the cytoplasm and are drawn with heavy outlines. 

 After Nansen ('87, Fig. 54). 



Fig. 10. Crayfish, Shows the chromophile bodies spindle shaped and apparently associated inti- 

 mately with the fibers. After Pflucke ('95, Fig. 10). 



Ntssl bodies in invertebrates. — The question as to the existence of NissL granules 

 in the nerve cells of invertebrates has more than once been raised. Pflucke 

 ('95) undertook the investigation of the finer anatomy of the nerve cells of the crab, 

 snails and worms. In the crab he succeeded in demonstrating granules which 

 appear like the commonly accepted Nissl bodies. In the snails and worms he 

 failed to identify such structures (Fig. 10). 



McClure ('97) found (chromophilous) granules in the nerve cells of Helix and 

 Arion, and expressed the opinion that this chromophilous substance is homologous 

 with that found in the nerve cells of vertebrates. 



Floyd ('03) was unable to differentiate by means of methylene blue any NissL 

 bodies in the ganglion cells of the common cockroach. In well fixed material, 

 however, he found varying quantities of deeply staining granules and masses. 



