124 TEIJI HOSHINO 



MICROSCOPICAL FINDINGS 

 1. Spinal cord 



The spinal cord of the pigeon has two enlargements, the upper 

 and lower intumescentia. The upper enlargement is located far 

 posteriorly, owing to the bird's long neck, and hence there is a 

 very short thoracic cord between the upper and lower enlarge- 

 ments (cervical vertebrae, 14, thoracic 4, lumbosacral 7 or 8, 

 coccygeal 5) . The upper enlargement has a larger diameter than 

 any other part of the cord. At the lower enlargement, the cord 

 is divided into two halves by the 'sinus rhomboidalis,' as named 

 by Kolliker ('02). The two halves of the cord are connected 

 at the lower part of the intumescentia only by the anterior white 

 commissure. According to Kolliker, this sinus is formed by ex- 

 tensive development of the sulcus dorsalis medialis in which 

 there is a gelatinous glial tissue. The ligamentum denticulatum, 

 a band of connective tissue which supports the cord from the 

 lateral edges of the vertebral bodies, appears at the level of the 

 lower enlargement well developed in the anterolateral portion of 

 the cord. 



White matter. All the sections of the spinal cords at the differ- 

 ent levels in the four affected pigeons are decidedly small in ref- 

 erence to both the white and gray matter as seen with the micro- 

 scope as well from the exact measurements, compared with the 

 sections from the corresponding levels of the normal control 

 birds. The myelin sheaths stained by the Pal-Weigert are gen- 

 erally slightly paler, so that each section of the affected. speci- 

 mens looks as if it were cut much thinner than the normal 

 section, whereas, in fact, they are both exactly the same in 

 thickness, as already indicated. Nevertheless, there is not found 

 any area in the funiculi totally without color by Pal's method. 



Throughout all levels of the spinal cord there is a relatively 

 pale area in the median portion of the anterior funiculus and in 

 the dorsolateral periphery of the lateral funiculus, while en the 

 other hand the whole dorsal funiculus is pale. The other 

 portions of the different funiculi do not exhibit any marked 

 color change. 



