544 THE SYMPATHETIC SYSTEM OF NERVES, BY DR. S. MAYER. 



number of small nuclei are surrounded by a small quantity only 

 of cell substance. Similar varieties of form may be observed 

 also in Mammals, as in the Rabbit, Dog, and Cat, though par- 

 ticular forms appear to predominate in each. I intend to revert 

 with greater detail to the significance of the relations just 

 described. 



The nucleolus is a structure that nerve cells usually exhibit 

 with extraordinary sharpness of outline. It is, however, 

 peculiarly distinct in the strongly pigmented cells of the adult 

 Man, where it shines out from the cloudy substance of the cell 

 and of the nucleus. Its position in the nucleus varies just as 

 that of the nucleus within the cell differs in different instances, 

 and, like this, the nucleolus is not unfrequently double or 

 multiple, the several nucleoli in the latter case presenting at the 

 same time a similar or varying magnitude. In the nucleolus 



Fig. 264. 



Fig. 264. Two multipolar cells, one from a child, the other from 

 an adult. 



itself a still smaller molecule may occasionally be observed 

 (Beale), the existence of which was originally noticed by 

 Mauthner in the cells of the spinal cord. Svierczewski 

 described movements in the nucleolus similar to the molecular 

 movements, which lasted for a considerable period if the 

 preparation were protected from desiccation. 



The presence of processes constitutes an important charac- 

 teristic of the sympathetic, as of the nerve cells of the central 

 organs of the nervous system. It was formerly maintained 

 by many observers that apolar cells, or cells destitute of pro- 

 cesses, occur in considerable numbers in the sympathetic ; but 

 at present the greater number of microscopists consider the 

 existence of apolar cells to be doubtful. It is certain that the 



