Smallwood and Rogers, Molluscan Nerve Cells. 65 



Our own work, done upon the living nerve cells, has convinced 

 us beyond any possibility of doubt of the actual existence of these 

 structures in the living cell. The detailed discussion of this fea- 

 ture appears later in the paper. 



Studies upon the molluscan nerve cells. — In a previous paper 

 in this Journal Smallwood ('06) described certain morphological 

 characters of molluscan nerve cells. Without indulging in vain 

 repetition, it is perhaps well to call attention here to certain of 

 these facts. There were found in the nerve cells of Haminea sol- 

 itaria, Venus mercenaria, Planorbis and Limax cytoplasmic vac- 

 uoles containing a colorless, transparent liquid, also solid bodies 

 of various sizes, irregularly rounded forms of varying numbers. 

 The solid bodies were of different appearance in the different 

 genera named, and somewhat different in distribution, those occur- 

 ring in Limax being always found within the limits of the vacuoles, 

 while in the other forms the bodies or granules were only rarely to 

 be seen in the vacuoles. Attention was called to the fact that 

 these bodies could be seen in the living nerve cell, and hence could 

 not be considered as artefacts. The fact that the number of 

 these bodies present in a given cell varies from time to time con- 

 vinced us that a morphological study could not satisfactorily 

 account for their presence and variable appearance. 



In our discussion of our work upon the bodies mentioned above 

 we do not wish to be understood as maintaining that these struc- 

 tures are in every sense homologous with the Nissl granules of 

 vertebrates. Morphologically and chemically they may not cor- 

 respond to the Nissl granules of vertebrates, and may even differ 

 much among themselves in these respects. We are convinced, 

 however, that the question of function is more fundamental and 

 believe that these structures will be found to fill the same place in 

 the economy of the invertebrate nerve cell as does the Nissl body 

 of the vertebrate nerve cell. 



Since the bodies found in the cells of Limax more nearly cor- 

 respond to those found in vertebrates we will first describe our 

 experiments upon this form and later discuss our work upon the 

 other forms under the caption "Pigment." 



Experijnental. — The experimental work in connection with our 

 study of the molluscan nerve cells has been carried out with a view 

 to determine, if possible, the nature of some of the structures which 

 have been found to exist in the cells. In order to insure a certain 



