284 THOS. H. MONTGOMERY, 



(Figs. 244 — 246, Plate 24). The form of the cell is very variable: 

 the greatest amount of the cytoplasm is in the vicinity of the nucleus, 

 and from that region are given off long, branching fibres. The general 

 shape of the cell is bipolar. Each such cell lies tightly wedged 

 between the germ cells (spermatogonia, spermatocytes), with resultant 

 irregular flattening and curvature. None of these cells showed any 

 signs of division. 



The nuclei (Figs. 244, 248) are of about the size of those of 

 medium-sized spermatogonia, but may be readily and in all cases 

 distinguished from them by their deeply-staining nuclear sap, and by 

 their angular outlines ; they have one or several more or less centrally 

 placed nucleoli. 



The cytoplasm has a very delicate structure, appearing sometimes 

 finely granular, sometimes reticular, often vacuolar. In it lie long, 

 smooth fibres (hence the name "fibre-cell") of various diameter 

 (Figs. 244—246 Fib), which are brought out very sharply by iron 

 haematoxyline staining, and are colored violet by Hermann's stain. 

 "Without disassociation preparations, for which there was not sufficient 

 material , it is difficult to follow the course of these fibres, for on 

 sections only portions of them can be seen. The middle region of 

 each fibre is the thickest, and probably it attenuates gradually at the 

 ends, since in the proximal and distal portions of the cell the fibres 

 appear thinnest. These fibres divide into smaller branches dichotom- 

 ously (Figs. 245, 246) ; but whether those of different cells anastomose 

 together could not be determined, since the membranes of these cells 

 are so delicate that cell boundaries are difficult to distinguish. The 

 course of each fibre is more or less parallel to that of the branch of 

 the cell in which it lies; but sometimes a fibre curves back on its 

 original course. There appear to be several of these fibres to a cell, 

 and a larger number of finer branches. Though these fibres stain much 

 more deeply than the muscle fibres or the testicular sheath, they may 

 be contractile in function. These cells are attached firmly to the 

 sheath of the testis, and their branches probably either anastomose 

 or closely interlace near the axis of the testis; thus the cell would 

 have two points of attachment, and its fibres by contracting might 

 serve to narrow the lumen of the testis, thus supplementing the con- 

 traction of the testis sheath. 



In the youngest testis examined these fibre-cells did not appear 

 more numerous than in the oldest; with the gradual increase in size 

 of the lumen of the testis (by the discharge of the spermatids into 



