782 



jections in the posterior poftioii are but faintly indicated. The septum 

 posterior lias nieanwliiie disappeared and tlie number of cells in 



Equus (Fig. 1). 



Equus (i''ig. '2). 



the anterior horn have greatly decreased, clusters of cells can be 

 seen longest ventraily and dorso-lateraliy on the border of the 

 anterior and posterior horns. In the sensory zone the large cells, 

 mentioned above, can still be seen, though not constantly, both in the 

 centrally situated cells and the fusiform border-cells. 



Likewise fairly large oval, or more or less round cells, containing 

 pigment, can still be seen occasionally. The (issura longitudinalis 

 anterior is unchanged. In the following portion of the sacral medulla 

 these conditions are the same, with the exception of the section of 

 the central canal. This is now widest in the ventral (anterior) por- 

 tion, for there the wall is gently curved ventraily or flattened, the 

 dorsal (posterior) pole a blunt curve, and the side walls exhibit 

 several bulges. These at first number two on either side, one half 

 way up and one on the ventraily pointing basis. In many sections 

 they are seen symmetrically. The number of cells in the anterior horn 

 has grown small again, while in the sensory zone the various kinds 

 of cells appear now and tiien as before. This sensory zone has grown 

 much more massive, owing to the commissura grisea having become 

 thicker, the fissura anterior is smaller and no longer shows the 

 broadeiied central portion. Further back the sensory horns merge 

 almost to one mass, in which however, the two horns can still be 

 separately distinguished for some time, as the round-fibred systems 

 keep their individuality (tig. 3). The conns which gradually decreases 

 in diameter, still exhibits the heartshaped form in section. The 

 anterior horn cells seen occasionally are few, and the central and 

 border cells are also scarce in the sensory area. The projections of 

 the central canal are larger, the epithelium is intact and soon a third 

 ^et of jjrojeclions makes its appearance. The number of cells de- 

 creases, especially in the sensory portion, while the section loses its 



