BRAINS AND SPINAL CORDS IN ATAXIC PIGEONS 121 



and the other normal, and both having the same thickness. 

 The two corresponding sections were then put on the same slide 

 and stained at the same time. This does away with any varia- 

 tion that could arise from the dye. In reference to the stains, 

 Weigert and Pal's modification, toluidin-blue-ery thro sin, Mann's 

 eosin-methyl-blue, haematoxylin-eosin, and Mallory's neuroglia 

 method were employed. 



• Thus, each affected section and normal control section has been 

 treated in exactly the same way from fixation to cutting and 

 staining, and we are able to compare any slight pathological 

 changes which might have taken place with much reliability. If 

 there are any artefacts or postmortem changes, which must oc- 

 cur to some extent, they will be present in both the affected and 

 normal specimen to the same degree. The findings observed in 

 each of the sections of all the birds will be here recorded together, 

 for the changes found are almost the same in all four affected 

 pigeons. 



MACROSCOPICAL FINDINGS 



The small size of the brain and spinal cord in all affected birds 

 can be recognized at a glance without any hesitation, especially 

 in the spinal cord, cerebellum, and medulla oblongata. The 

 length of the spinal cord and the weight of the different parts of 

 the brain and cord may be seen in tables 1 and 2. 



As is seen in the tables, the weights of the brain and spinal 

 cord are not only absolutely less in the affected pigeons, but less 

 in proportion to their body-weights. In the affected pigeons, 

 moreover, there is much more reduction in weight of the distal 

 portion of the brain which includes the cerebellum and medulla 

 oblongata chiefly, but also a part of the midbrain and the lower 

 third of the optic lobe than of the proximal part of the brain which 

 is the cerebrum chiefly. Again, the ratio between the weight of 

 the distal portion of the brain to the whole brain in the affected 

 pigeon is always less than the ratio between the weight of the 

 distal portion of the brain to the whole brain in the normal 

 pigeon. The same relation holds for the spinal cord. 



