NERVOUS TISSUE. 



108 



and regulatory influence on the life and function of the nerve 

 cell (Marinesco). It is possible that they are products of 

 metabolism. In favor of this idea is the work of Lugaro, who 

 found that in chronic arsenic poisoning there are definite 

 changes in these tigroid bodies. Changes in these occur also 

 in various diseases. 



Around the nucleus a network of fibrils has been recog- 

 nized by Apathy, Bethe, and others, which are, according to 

 them, continuous with the fibrils of the axone. 



FIG. 73. 



Demlritex 



Chrom atophilic 

 granules 



Nerve cells from the anterior horn of the spinal cord of a calf. Chromatophile granules 

 are stained in methylene blue by the method of Nissl. X 950. 



A centrosome is found in spinal and sympathetic ganglion 

 cells, but is usually not to be made out in other nerve cells. 

 Yellow-brown pigment is found often in the protoplasm. 



The nucleus of the nerve cells is characteristic. As a rule, 

 it is single, large, and vesicular. It possesses a distinct cell 

 membrane, usually a large nucleolus, and only a small quantity 

 of chromatin. 



A true cell membrane is not present. Cells which are 

 situated peripherally, however, usually possess a secondary 

 capsule of connective- tissue origin. 



