Langdon, Sense-organs of Nereis virens. 3 1 



These pericellular baskets are apparently formed of deep 

 blue branching and anastomosing fibers which lie within the 

 capsule of the enclosed ganglion cell either just on or above the 

 surface of the latter (Plate II, Fig. 39). The individual fibers 

 are generally beaded or coarsely varicose and closely resemble 

 the nerve-fibers in these same preparations. Sometimes an ap- 

 parent nerve-fiber can be traced along the axis cylinder of the 

 ganglion cell and directly into one of these pericellular baskets 

 (Plate II, Fig. 40). In all cases in which the wall of the en- 

 closed ganglion cells is wrinkled, the fibers of its basket are sit- 

 uated upon the summit of the folds due to this wrinkling. 

 When the basket is but little more deeply stained than the cell 

 itself, this apparent network is probably the optical section of 

 the wrinkles. In other cases the difference in depth of color 

 between the stains of the walls of the ganglion cell and that of 

 the pericellular basket is too great to be accounted for by a 

 mere fold of the former. If one looked through a pale blue 

 membrane so wrinkled as to show anastomosing ridges sepa- 

 rated by intervening depressions, the colored material through 

 which the light would pass to meet the eye would be of greater 

 depth in the ridges than in the depressions between them. 

 This greater depth in material would give a proportionally 

 greater depth in color. 



At Professor Reighard's suggestion, I tried an experiment 

 which seems to show that such an explanation as the above will 

 not account for the apparent dark network lying on the surface 

 of a light colored ganglion cell. I placed under the microscope 

 a pale blue ganglion cell which was surrounded by a dark blue 

 network. I then took a thin-walled glass tube and poured into 

 it enough of a light-colored methylene blue solution to give, 

 when one looked into the tube and consequently through the 

 depth of fluid, just the pale blue color of the cell wall. After 

 noting the depth of this solution, I poured in enough more of 

 the solution to give just the deep blue color of the network and 

 compared it with the first mentioned depth. I then measured 

 the thickness of the cell wall itself and that of an apparent fiber 

 of the network. If the apparent fiber were a ridge of the cell 



