492 E. V. Cowdry, 



fibrils in Cajal preparations which have been toned with gokl chloride 

 and counterstanied with safranin (fig-. 8). 



Nelis (1899) described a system of canals in nerve cells which 

 he termed „spiremes" and regarded as indicative of pathological con- 

 ditions. Sections fixed in 7^/^ formalin were stained in iron hema- 

 tox3din and Böhraer's hematoxylin according to his directions (1900, 

 p. 613). Such preparations showed the canals with great clearness, 

 and the three types, the diffuse, the circumscribed excentric, and the 

 circumnuclear could be distinguished. Compare figures 19, 20 and 21 

 with Nelis, 1900, plate XXVII, figures 15 and 22. 



Holmgren has also carefully studied these clear canals. Prepara- 

 tions were likewise made by his methods, the canals being seen 

 after the following fixations: picric acid sublimate, sublimate-acetic, 

 and Carnoy's 6:3:1 fluid (Holmgren, 1899, p. 389—390). In addition, 

 specimens were fixed in trichlorl actio acid and stained with Weigert's 

 resorcin-fuchsin as directed by Holmgren, 1901, p. 297. By this means 

 the canals became coloured a dark purplish black (fig. 36). The reac- 

 tion was far from constant, however, as a complete series of grada- 

 tions could be seen in a single section between cells in which the 

 canalicular apparatus was not stained at all, and those in which it 

 was almost completely stained (figures 34, 35 and 36). Figures 22, 

 23 and 24 have been drawn from another spinal ganglion fixed in a 

 stronger solution of trichlorlactic acid and stained in the same fashion. 

 In them the canals are uncoloured. They illustrate the three char- 

 acteristic types of canalicular formation referred to above. Compare 

 these figures with Holmgren's illustration of a spinal ganglion cell 

 fixed in Carnoy's fluid and stained with resorcin-fuchsin, 1900, fig. 3. 



Kopsch (1902) demonstrated the reticular apparatus by subjecting 

 tissues to the action of a 2^/^ solution of osmic acid for several days. 

 Specimens were prepared in this way and the configuration of the 

 blackened reticular apparatus studied. As in the case of the clear 

 canals, so also here, diffuse, circumscribed excentric, and circumnuclear 

 types of network could be distinguished in the large, medium, and 

 small cells respectively (figs. 25, 26 and 27). The jet black strands 

 of the network present a worn and ragged appearance in contrast to 



