BRAINS AND SPINAL CORDS IN ATAXIC PIGEONS 125 



The one in the medial portion of the funiculus ventralis is 

 shaped like a right triangle with the right angle in the corner be- 

 tween the edge of the cord and ventral sulcus. The triangle is 

 elongated ventrodorsally and narrow frcm side to side in the 

 upper cervical region, but it is broad from side to side and narrow 

 ventrodorsally in the lower enlargement. This area is present 

 in both normal and affected specimens, but in the affected ones 

 the boundaries are quite indistinct. The normal has fibers of 

 almost uniform caliber in this area, but in the affected one the. 

 fibers are small on the average and vary in size (tables 3 and 4) . 

 In addition to this, there are many small fibers under 2.8 n in 

 caliber in the affected birds. So many small fibers in this area 

 are not observed in the normal preparations. They have all 

 about the same size and their myelin sheaths stain deeply. 

 These differences of the myelin sheaths and the variable caliber 

 of fibers of the affected specimens no doubt give rise to the pale 

 appearance and to indistinct boundaries of this area. The great- 

 est transverse breadth of the funiculus anterior is reduced in all 

 the affected specimens. Nowhere is there any apparent sign of 

 the degeneration of the fibers, however. At the lateral portion 

 of the anterior funiculus of pigeon no. K172, just at the place 

 where the anterior rootlets pass through the white matter, from 

 the ventral horn, the longitudinal fibers are arranged loosely. 



The second area at the lateral periphery of the lateral funiculus, 

 just dorsal to the dorsal horn, is long and crescent-shaped with 

 its base toward the periphery. At its median side, it is bounded 

 by an area of fibers of large caliber. This portion in the affected 

 specimens is reduced in both the transverse and ventrodorsal di- 

 ameters and is light blue in color; the myelin sheaths are thinner 

 and the caliber of fibers is much smaller than normal, as is seen 

 in tables 3 and 4. In the lower enlargement the fibers measure 

 2.9 to 7.1 n in the normal and in the affected specimen 2.2 to 

 5.1 /it. 



The third area indicated as being' the funiculus dorsalis, in 

 addition to its pale color, has a brownish to red color when count- 

 restained by erythrosin, instead of the deep blue-black of the 

 normal section. It must be noticed here that usually the funic- 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 31, NO. 2 



