276 Scientific Proceedings^ Royal Dublin Societp. 



and transferred to Cajal's reducer for two days. They were then again quickly 

 washed and embedded in paraffin. The method of Cajal was also employed with 

 success. 



Champy-Kull fixation followed by Champy-KuU staining or iron-hasmatoxylin 

 was very valuable, as was also Flemming-without-acetic-acid and iron- 

 heematoxylin technique. 



Good results were obtained by the Mann-Kopsch method. The material was 

 fixed in the osmo-sublimate solution for one hour and impregiaated with 4 per cent. 

 OsOi for 14 days. Subsequently some of the sections were extracted with 

 turpentine for some days, and stained with Altmann's acid-fuehsin. 



Material was also fixed in 10 per cent, neutral formalin for two days, or in 

 90 per cent, alcohol for one day, both methods being followed by iron-hamatoxylin 

 staining. Petrunkewitsch was used, followed by toluidin blue, warmed on the 

 slide. 



The live ganglion cells were carefully examined in their own lymph, and 

 also stained with Soudan III. in 70 per cent, alcohol, Dahlia 0-75 per cent, in 

 0-75 per cent, salt sol., Bismark brown in 1 per cent, acetic acid, Janus green 1 

 in 10,000 (approximately) and 1 per cent, osmie acid. 



III. — General Description of the Ganglion Cells. 



Neurones at eveiy stage of development can be found, at the same time, in 

 the cephalic ganglion of the adult Helix. The smallest of these measure little 

 over 7/i in diameter, while the largest attain a size of over 110 /.i 



In preparations of the living ganglion cell, mounted in its own lymph, the 

 axon and numerous branched dendrons are well seen. The cytoplasm of the 

 body of the living cell appears coarsely granular. On the average the diameter 

 of the nucleus is about two-thirds of that of the whole cell; this proportion 

 remains approximately constant no matter what the actual size of the cell may be. 

 In all the successful silver preparations it was observed that the majority of the 

 nuclei did not take the silver, while other nuclei were deeijty impregnated, the 

 chromatin granules showing up well. The nucleoli failed to take the silver even 

 in the most deeply impregnated nuclei. 



IV. — The Golgi Apparatus. 



The silver methods of Da Fano and Cajal and the Mann-Kopsch osmium 

 technique impregnate well the Golgi apparatus in the nerve cells of Helix. 



In the smallest neurones observed, the Golgi apparatus was in the extra- 

 centric juxta-nuelear position (PL XVII, fig. 1). At this stage it consists of a 

 large number of curved rods, lying on an archoplasmic sphere. This apparatus, 

 at a slightly later stage, divides, the resulting portions tending to pass around 

 the nucleus (fig. 2). The breaking up and scattering continues, the apparatus 

 passing through a stage (fig. 3) consisting of a number of archoplasmic discs, 

 each surrounded by three or four rods. At the end of this process all the rods, 

 each with a portion of archoplasm filling its concave side, are separated and 

 scattered completely around the nucleus. After this no further change takes 

 place, but with the growth of the cell they greatly increase in number (figs. 4 

 and 5). In a large neurone the number of Golgi rods, some of which are straight, 

 others curved or ring-shaped, is enormous. They form a zone around the nucleus, 

 and pass out some distance into the dendrons, but are not found in the periphery 

 of the cell. They are not found in the axon or axon-hillock, and are much fewer 

 and markedly smaller in the region between the hillock and the nucleus (fig. 5). 



