486 F. W. GAMBLE AND J. H. ASHWOETH. 



specimen 78 mm. long, and the result is given in PI. 29, fig. 79. 

 There are no giant-cells in the brain. The first one occurs at 

 the point of union of the oesophageal connectives well in front 

 of the first chsetigerous segment, and it therefore probably 

 belongs to the (in the adult) achaBtous segment immediately 

 following the peristomium. In the second and third chse- 

 tigerous segments there is only a single giant-cell, while in 

 the fourth segment the posterior of the two cells is represented 

 by two rather small ones close together side by side. Behind 

 this point the arrangement is uniform, being subject merely 

 to slight irregularities in position. In one segment (thirty- 

 fifth), however, the cells are absent. In the last segment two 

 small cells are present. 



In sections of the cord, the giant-cells occupy an almost 

 median and ventral position among the ganglion-cells which 

 cover the lower surface. On the average each giant-cell 

 occupies a third of the width of the cord in transverse or 

 horizontal sections, and at the level of the nucleus measures 

 50 to 80 jjL in diameter. The real shape of the giant-cells is a 

 pyriform one, and the narrow extremity is placed laterally and 

 prolonged upwards into the fibrous matter of the cord. On 

 the evidence of the methods we have successfully employed, 

 this process appears to be the only one given off from the 

 giant-cell in every case. 



The structure of the body of the cell merits detailed descrip- 

 tion. First there is a nucleated fibrillar sheath of neuroglial 

 nature. In horizontal sections the nuclei are flattened parallel 

 to the surface of the cell ; when transversely cut, however, 

 they appear more circular. Externally the limits of this 

 fibrillar sheath are not well defined. They merge imper- 

 ceptibly into the glia network which fills the interstices 

 between the surrounding cells. The fibrils of this sheath 

 give all the appearance in response to haematoxylin and 

 haeraatein stain that are attributed to them by Apathy (1898) 

 in the sheath of ganglion cells of the leech and earth- 

 worm. Of these appearances the most impoi'tant are their 

 extensions between the surrounding ganglion cells already 



