148 Journal of Agricultural Research Voi. xviii.no. 3 



Besides the general nuclear stains for cell protoplasm, selective stains 

 were used, as the Van Gieson's stain, Nissel's stain, Pal's modification of 

 Weigert's myelin stain, and Marchi's method of staining fatty degenera- 

 tion in the myelin sheaths. 



MANIFESTATIONS OF DOURINE 



In reviewing the etiology of dourine we find that the unicellular proto- 

 zoan Trypanosoma equiperdum is considered the cause of dourine. It is 

 apparent that the disease, being transmitted in the act of coition, should 

 show the principal lesions in the genital organs. But in all chronic cases 

 of dourine, besides the lesions in the sexual organs pronounced derange- 

 ments of peripheral nerves and the central nervous system are present, 

 manifested by paralysis of nerves and atrophy of various groups of 

 muscles. As trypanosomes can be found neither in the central nervous 

 system nor in the peripheral nerves it must be assumed that the try- 

 panosomes elaborate poisonous products or toxins which are responsible 

 for the lesions. The presence or absence of lesions in acute cases will 

 not be discussed, since all the obser^'^ations v^ere confined to chronic 

 cases, nor will the symptoms and post-mortem examination be described 

 in this paper. 



The following tissues were selected: Brain, spinal cord, spinal ganglia, 

 and peripheral nerves. No detailed study of muscles, skin, and genital 

 organs was undertaken, though some preparations of these structures 

 were made. 



BRAIN 



A number of pieces were taken from various parts of the brain, prin- 

 cipally in the region of the lateral fissure (Sylvius), supersylvian fissu :, 

 perisilvan fissure, and the sulcus rhinalis. Some of the sections w 

 stained by the Van Gieson method, others with the Erythrosin-tuo. 1 

 blue method. Both methods are used to study the general morphology 

 of nerve structures, particularly the cell bodies of neurones. The nuclei 

 appear bluish red, the ganglion cells and their protoplasmic processes 

 red, the axis cylinder brownish red, the myelin sheaths yellow, the 

 neuroglia fibers orange red, and the connective fibers deep red. 



The sections from the different parts did not reveal any appreciable 

 abnormality either in the nerve cells and their pericellular lymph spaces 

 or in the blood vessels and their perivascular spaces. The cell and the 

 nucleus took the stain uniformly; their size and external contour were 

 unaltered. The blood vessels also appeared normal. Staining with the 

 Nissel method showed no change in the chromatophil granules; neither 

 was their amount or size increased or diminished. There was no change 

 in regard to the staining ability or grouping of the nucleus or any indi- 

 cation of chromatolysis. Staining with Pal's modification of the Weigert 

 method showed good contrast of the gray and white substance but no 



