PRELIMINARY REPORT ON THE CYTOLOGY OF 

 MOLLUSCAN NERVE CELLS. 



W. M. SMALLWOOD. 

 With Seven Figures in the Text. 



The observations now reported are on the Opisthobranch, 

 Haminea, the LameUibranch, Venus, and the Pulmonates Planor- 

 bis and Limax. In addition to these forms Helix, Littorina, 

 Melantho, Montagua gouldii, Aplysia and others have been 

 worked during the past three years. 



Interest in the structure of the cytoplasm not only of the nerve 

 cells of both vertebrata and invertebrata but in gland, epithelial, 

 egg and sperm cells has resulted in the accumulation of a very 

 considerable literature during the past ten years and more especi- 

 ally the last five. (See Holmgren, 'oi; Rhode, '98, '03 a, '03 b, 

 '04 a, '04 b; Bergen, '04, and others.) Sufficient facts have been 

 advanced by these writers to indicate that here are a large and 

 varied number of conditions existing in the nucleus and especially 

 in the cytoplasm of adult cells. My purpose is to refer but briefly 

 at this time to these structures in nerve cells, reserving for the full 

 paper a more extended survey of the literature. 



The structures already found in the nerve cells of vertebrata and 

 invertebrata are given a variety of names in part at least due to the 

 theory of their origin and fate. These may be grouped under two 

 headings for convenience in description, although in some instances 

 at least the two classes are interrelated. 



1. The lymph spaces which have no constancy of form or 

 position in nerve cells, sometimes being found near the nucleus, 

 or in the vicinity of the periphery of the cell, or again having a 

 general distribution. Some writers regard them as artefacts 

 while others maintain that they are normal and essential to the 

 cell activity. 



2. In this second class may be placed a large variety of bodies 



