ANATOMY AND CLASSIFICATION OF THE3 ARENIC0LID7E. 489 



stained with h^ematein 1 a or iron haematoxylin) they can be 

 followed from the base of the cell-process round the body of 

 the cell, and can be seen to divide and penetrate into the 

 layer which lies inside the outer alveolar zone. They do not, 

 however, seem to reach the nucleus, but are limited to the 

 more superficial layer of the granular aud, it may be, slightly 

 alveolar protoplasm. In some cases the processes of these 

 neuro-fibrillee appear to terminate in the central granular 

 network of the protoplasm, but this is probably mere contact. 



In order, however, that these " neuro-fibrillee " should 

 thoroughly conform to the structures which Apathy has so 

 named, it ought, according to this author, to be shown that, 

 after branching at the broad end of the cell, they again unite 

 and run a recurrent course along the cell process, and so 

 through the fibrous part of the cord to muscle or gland. 

 This we are not able to show. But we believe that we are 

 able to distinguish these " neuro-fibrillse" by their course, 

 and especially by their relation to the cell process from the 

 histologically similar glia-fibrillte, which, as we have seen, 

 either penetrate but a short distance from the sheath into the 

 outer alveolar layer, or more rarely form a more complete 

 network within the cell substance. 



To further determine the character of these giant-cells it 

 is necessary to examine the nature and course of the cell 

 process. We are only able to demonstrate one stout process 

 to each giant-cell, forming, so to speak, the stalk of the cell. 

 The fine granular contents of this stalk do not stain ; they 

 contain '' neuro-fibrill?e," and they are ensheathed in a fibrous 

 envelope of a deeply staining character. The process so 

 formed runs a somewhat sinuous course through the fibrous 

 part of one side of the cord towards the upper surface. 

 Shortly after leaving the cell it gives off a branch to the 

 outer side of the cord, and further on another. These 

 branches end apparently in the fibrous region of the cord, 

 and are not invariably present. When the cell-process has 

 arrived near the median dorsal line of the cord its further 

 course varies according to the region of the body with which 



