114 HUNTER, [Vol. II. 



Summary. 



The principal points treated in this paper are as follows : 



I. The demonstration of the fibrillar nature of the nerve 

 process as opposed to the " nerve tube " of Nansen. Positive 

 proof of the elementary network of Apathy and Bethe is lack- 

 ing. Such a view could, however, best explain the structure of 

 the neuropile of the ganglion (brain) of CyntJiia. 



II. The presence in the nerve cell of ganglion bodies of 

 different size, which color strongly with methylen blue and 

 which are of different chemical structure from the groundwork 

 of the cell. These bodies are undoubtedly homologous with the 

 chromophilous substance in many invertebrates (Pfluge,McClure) 

 as well as in vertebrates. The ground substance of the cell 

 appears granulo-fibrillar. Frequently fibrils may be proved in 

 the cell, especially near the process, and in the periphery of the 

 cell. A cone of entrance was frequently found. 



III. The existence of the centrosome and sphere in the 

 ganglion cell. This structure was found in adult as well as in 

 young specimens killed a few days after metamorphosis. In 

 the young cell the structure more frequently existed without 

 radiations, and with little or no cytoplasmic condensation about 

 the central body or bodies. The centrosome was proved in a 

 greater proportion of cells in young specimens. In older speci- 

 mens the centrosome and sphere, although not limited to cells 

 of certain size, was proved in fewer cells proportionately. 

 When found it exhibited all possible variations from the central 

 body with little or no cytoplasmic condensation to a decided 

 sphere with cytoplasmic radiations extending almost to the 

 periphery of the cell. In the latter case the nucleus was deeply 

 invaginated and pushed far to one side of the cell, while in cells 

 with little or no radiation and small sphere the nucleus was 

 often ovoid, or only slightly flattened. 



It is hoped in a later paper to give a more complete account 

 of the fibrillar structure of the nerve trunks, and to throw some 

 light, if possible, on the function of the centrosome in the 

 ganglion cell. 



Hull Zoological Laboratory, 

 May 15, 1898. 



