THE NERVE CELL 



I8 5 



of the cytoplasm. Some are fatty in nature and others appear to be 

 coagulated lymph or blood that was in the cell at the time, particularly 

 in the channels 

 that are described 

 below. 



Many nerve 

 cells are among f\^-&&l^-$"}*-\.- 



conn.t. 



gr. 



FIG. 162. Large nerve cells from sub-oesophageal ganglion of Helix, 

 conn.t., connective-tissue elements invading cytoplasm; gr., gran- 

 ules in the cell channels. X3<x>. (From a preparation by McCLURE.) 



"^tf?"Wfl4 



^R4o 



among ^ v - ,-.-. >- , ... -... ,. 

 those animal cells 

 that approach the 

 limit of size that a 

 cell can attain and 

 still have surface 

 enough to perform 

 its nutritive and 

 excretory ex- 

 changes. A few 

 go above that size 

 and in conse- 

 quence are obliged 

 to develop in their 

 cytoplasm a set of 

 channels that will 



serve to increase this power of exchange. Among these are many 

 nerve cells that possess lymph channels or spaces of various degrees 

 of size and efficiency. These lymph channels can be seen, weakly de- 

 veloped, in the sympathetic 

 ganglion cells of the musk- 

 rat (see Fig. 158), and more 

 strongly shown in the larger 

 nerve cells of the squid (Fig. 

 156), in which latter form 

 they also are occupied, in 

 part, by the connective-tissue 

 fibrils that penetrate the cell 

 substance. More exceptional 

 is the case of the giant 

 dorsal nerve cells of the pe- 



FlG. 163.- Spinal ganglion nerve cell from electro- diculate fishes, in which the 

 cuted man. pg., pigment mass lying in cytoplasm capillaries themselves, with 

 next to implantation cone. X 1000. their ^ of connect ive- 



tissue cells, enter the cytoplasm of the cell and supply it with a medium 

 of exchange (Fig. 161). 



It has been noted above that connective-tissue fibrils enter the neuro- 



