RAND: NERVOUS SYSTEM OF LUMBRICID.E. 89 



The cytoplasm is arranged concentrically around the sphere, showing 

 a differentiation into an endoplasm and an exoplasm. The endoplasm 

 is finely granular, the granules being more concentrated toward the 

 centre. The exoplasm gives up its stain more readily than the endo- 

 plasm, remaining diffusely stained and appearing less granular than the 

 endoplasm. 



The conditions described were found in only the smaller cells of the 

 ganglia. No centrosome was found in the spinal-ganglion cells of 

 the dog or cat, but a concentric arrangement of the cytoplasm about 

 the nucleus, which in those animals was found generally at the cell 

 centre, was observed, leading von Lenhossek to suggest (p. 368) that 

 '• das dynamische oder vielleicht auch morphologische Aequivalent des 

 Centrosoms hier in den Kern verlagert ist." No radiations were seen 

 by von Lenhossek. All of his figures are from preparations fixed 

 in sublimate and stained by Heideuhain's bordeaux-iron-hsematoxylin 

 method. 



Biihler ('95), working simultaneously with von Lenhossek, announced 

 the discovery of " Centralkorper " in the cortex of the fore-brain of the 

 lizard, and also in nerve cells of the human brain. Biihler used warm 

 corrosive sublimate and Flemming's fluid as fixing agents, and stained 

 in various aniline dyes. His best demonstration of the " Centralkorper," 

 however, resulted from the use of Heideuhain's iron-haematoxylin with 

 bordeaux, safranin, or rubin. 



Biihler found the nuclei to lie generally nearer the end of the cell 

 from which the process came off, frequently so close to the surface " dass 

 er stellenweise die Zellgrenze zu bilden scheint" (p. 17). On the side 

 of the nucleus toward the greatest cytoplasmic mass, and therefore 

 opposite the nerve process where that is to be seen, appear from one to 

 three small, intensely stained granules, lying close together, and some- 

 times connected by a " Substanzbrtlcke." About this granule or group 

 of granules is a clearer area of cytoplasm, and there may be one or 

 several more or less complete dark circles concentric about the central 

 granules. Radial fibres often appear extending out from the central 

 granules, sometimes only to the inner of the surrounding circles, and 

 sometimes quite to the periphery of the cell. Each of these concentric 

 circles is due to a series of varicosities on the radial fibres, at equal dis- 

 tances from the central granules. In some preparations, however, the 

 radial fibres are not conspicuous, and the circles appear to be made up 

 of rows of granules. 



Other systems of fibres run more or less parallel to the cell surface, 



