Meyer, Data of Modetn Neurology. 257 



hypoglossal nucleus are present in normal number and size, and 

 fibers come from it which constitute the hypoglossal root. On 

 the left side, these fibers are absent and also all the cells of the 

 nucleus. The two nuclei of the pneumogastric are normal and 

 symmetrical, and also the small celled nuclei of Roller along the 

 ventral border of the hypoglossal nuclei. Therefore, they do 

 not belong to the hypoglossal nucleus. This is one part of 

 our evidence. Another point of evidence is obtained by a sim- 

 ple section of the hypoglossal nerve before it enters the tongue, 

 in an adult animal which is allowed to live two or three weeks. 

 The hypoglossal cells of the side on which the nerve was cut, 

 all show a peculiar alteration with the Nissl-stain. In order to 

 understand the change we must proceed to describe the ' equiv- 

 alent ' of a normal hypoglossal cell as obtained by the method 

 of Nissl. The hypoglossal cell has a large nucleus with large 

 nucleolus, located near the center of the cell. The nuclear 

 membrane is rarely visible, being covered up by characteristic 

 lumps of stained substance which are arranged in a typical man- 

 ner within the cytoplasm and the dendrites, more or less com- 

 pact portions of a stainable substance being separated by channels 

 of non-stainable substance, more or less parallel to the outline 

 of the nucleus and also to the outline of the cell-body and 

 largely longitudinal in the dendrites. In a few of the cells, the 

 section exposes a small area on the surface which contains no 

 stainable lumps and from which a faint process arises, the neu- 

 rite, free of stainable substance. On the normal side of our 

 section the cells all show this arrangement although in the detail 

 of outline of the cell, form and size of the * granules ' and 

 presence or absence of the nerve-cone the individual cell-pictures 

 vary greatly. On the side on which the hypoglossal nerve was 

 cut, the cells show a peculiar change. At first sight they ap- 

 pear swelled and more diffusely stained than those of the nor- 

 mal side. The stainable substance is in a process of decay and 

 covers up the channels of non-stainable substance. The nucleus 

 becomes more visible, its membrane is no longer covered up 

 by the lumps. Other cells show a marked swelling and the 

 center is taken up by a more or less glassy slightly dusty tissue 



