( 89 ) 



the preparations stained after Bielschowskt. Where the neuroftbrillae 

 were visible, they formed a network. In my preparations stained 

 with chloride of gold after Apathy, which I looked over for these cells 

 I however found them again. The uninterrupted course oftheneuro- 

 fibrillae was clearly to be seen. They are however only very rarely 

 met with. 



So we find in nearly all the cells a network of nenrofibrillae 

 with regular meshes. In full-grown animals the meshes in different 

 cells are of about the same size. But when we examine the same 

 kind of cells (for example the colossal ganglion cells) in very small 

 animals, we find a neurofibrillar network of the same regularity bul 

 with much smaller meshes. So when we compare fig. 1, a colossal 

 ganglion cell of a fullgrown Branchiostoma of 48 m.m. in length, 

 with fig. 3, an analogue cell of an animal of li m.m. in length, we 

 find a much smaller-meshed network. Those small animals have 

 finished their metamorphosis already, and present nearly the same 

 organisation as the adult animal. The nerve-cells therefore seem to 

 have assumed already the definite arrangement of their neurofibrillar 

 structure, but the meshes are much smaller. During the following 

 growth of the nerve-cells the reticulum grows, but the structure 

 remains the same. In different adult specimens the size of the meshes 

 seemed always to be of the same order, and only to present the 

 slight differences mentioned above. 



When we compare this with the neurofibrillar structure, described 

 for the ganglion cells of other animals, I will here especially call 

 attention to the description of Apathy for Hirudineae and Vermes, 

 of Bochenek for Helix, of Doxagoio, Cajal, Michotte, Legendre and 

 the many authors, who have studied the ganglioncells of the higher 

 vertebrates by means of the new elective histological methods. Among 

 the descriptions by these authors of the neurofibrillar structure in 

 the nerve-cells of the representatives of different classes of the animal 

 kingdom, that of Branchiostoma takes just the place, we generally 

 give to that animal in the animal series. Is fig. 7 is drawn a 

 sensory cell of a Pontobdella, with the neurofibrillar structure stained 

 after Apathy. We see a very coarse network around the nucleus, 

 with fibrillae radiating to the periphery and forming there a second 

 network. The ganglion cells of Helix give according to Bochenek 1 ! 

 a much finer network. The meshes of this network are still much 

 larger than those of the nerve-cells of Branchiostoma; these in their 

 turn are larger and the fibrillae coarser than the neurofibrillar struc- 



]) Le Nevraxe, Vol. Ill, Fasc. 1. 1901. page 85. 



