90 BULLETIN: MUSEUM OF COMPAKATIVE ZOOLOGY. 



or coucentric to the nucleus, and are traceable out into the processes. 

 These fibres, which Btihler believes to be limited to the surface of the 

 cell, also bear varicosities and appear to intersect the radial fibres, the 

 points of intersection being marked by " kleine Knotchen." The cen- 

 tral granules Btihler believes to correspond to the " Centralkorper " of 

 Heidenhain, and the radial fibres to Heideuhain's " organische Radien." 



As to the function of the centrosome in the resting cell, Btihler says 

 (p. 37) : "Wo, wie in reifen Ganglienzellen ihre Beziehung zur Zelltei- 

 lung nicht nachgewiesen werden kann, da tritt ihre zweite Function 

 in ihre Eechte : Sie sind in der ruhenden Zelle die Insertionsmittel- 

 punkte fiir das centrirte Fibrillensystem." Biihler states (p. 38) his 

 belief that " nicht nur das dynamische Centrum der Zellteilung in Ge- 

 stalt der Centralkorper, sondern das gesaramte System der organische 

 Radien einschliesslich der Attractionssphare dauernd in ruhenden Zellen 

 sich erhalt." 



Dehler ('95) described structures in the sympathetic-ganglion cells 

 of the frog very similar to those described by von Lenhossek for the 

 spinal-ganglion cells of the same animal. Dehler, like von Lenhossek, 

 obtained his best results with sublimate fixation and Heidenhain's stain- 

 ing methods. He found the nuclei excentric and lying at the end of the 

 cell opposite the nerve process. They are generally flattened or concave 

 on the side toward the cell centre. The cytoplasm contains " Schollen 

 die sich conceutrisch im Zellleib zu einander reihen." The centre about 

 which the " Schollen " are arranged is approximately the centre of the 

 cell. They are generally larger toward the periphery of the cell. • The 

 central region of the cell is more often quite free from them, and they 

 are less marked, or even absent, in the smaller cells. 



At the centre of the ceil lies the " Centralkorpergruppe," composed 

 of several deeply staining granules. About them the section of the cell 

 exhibits a well-defined circular clear area from 5/i to 7/i in diameter. 

 It is very finely granular and is bounded by neither a membrane nor a 

 row of granules. In some of Dehler's figures there is about the central 

 clear area a considerable zone free from the coarse "Schollen." In 

 other cases the " Schollen " extend quite to the boundary of the clear 

 area, which corresponds to von Lenhoss^k's " SphJire." Dehler found 

 no radiations from the region of the centrosome. 



Flemming ('95*) described a concentric arrangement of granules 

 about the nucleus of the spinal-ganglion cells of mammals, but he found 

 no structures similar to the centrosome and sphere which then had been 

 recently described l)y von Lenhossek in the frog. 



