150 ANNUAL REPORT OF THE Off. Doc. 



always without result. We were led to tlie present investigation 

 iiiore than a year ago while making a study of the value of the 

 rapid diagnosis of rabies after the method of Van Gehuchteu and 

 N^lis, in the course of which several horses and two calves, which 

 had died of forage poisoning, were used as controls. 



Pathological Keport. — AVith the excei^tiou of the lesions in the 

 upper gastro-intestinal tract where the infection probably occurs, 

 the only others discovered were confined to the central nervous 

 system, and may be grouped for purposes of description as follows: 



1. Lesions of the intervertebral and Gasseriau ganglia. 2. Le- 

 sions in the cerebral and cerebellar cortex. 3. Lesions in the cho- 

 roid plexuses of the lateral cerebral ventricles. 4. Lesions of the 

 peripheral nerves supplying the larynx. 



Fifteen animals have been studied. In the first six of these the 

 intervertebral ganglia were not examined. In all the nine cases 

 in which these structures have been studied the following changes 

 have been found: In the normal ganglion the ganglion cells are en- 

 closed in a capsule titting closely around the cell. This capsule is 

 made up of a single layer of endothelial cells. The supporting 

 structure of the ganglion is composed of a loose areola of connect- 

 ive tissue, through which run the nerve fibers on their way to the 

 spinal cord. All of these structures are affected. 



The ganglion cells were the seat of extensive chromatolysis. The 

 degenerative changes vary from a simple diffuse chromatolysis — 

 a fusing together and loss of outline of the fine chromatin points 

 in the cell protoplasm — to complete destruction of the cell body 

 and nucleus. At times cells were found apparently normal, except 

 for the accumulation of large amounts of a yellow pigment, stain- 

 ing black wdth osmic acid. In other cells, besides the diffuse chro- 

 matolysis above referred to, the nucleus was found displaced to the 

 periphery of the cell. As the degenerative changes advanced, the 

 cell protoplasm took the stain very strongly and appeared a deep 

 blue by the Nissl method. Marked vacuolatiou of the cell proto- 

 plasm was present in two cases. In four cases some of the gang- 

 lion cells were completely disintegrated, filaments of protoplasm 

 remaining among the small mononuclear cells surrounding the cap- 

 sule. 



Capsular and pericapsular changes. — In nil nine cases in which 

 tlie intervertebral ganglia were examined a ]>eri-capsular, small 

 round cell accumulation was present. In some of the degenerating 

 ganglion cells a few nuclei were seen within the capsule in the de- 

 generating cell protoplasm. The accumulation of nuclei around the 

 cell capsule did not always assume a concentric shape, but was 

 often eccentric extending irregularly into the stroma. The cells are 

 all of the small type, the nuclei and the proto})lasm being about 



