aO DEPARTMENT OF AGRICULTLRE 



reason why the parasite cannot be observed in all clinical cases. This difficulty is 

 experienced in all affections causwl by trypanosomata and it is my belief that we still 

 have much to learn concerning the life cj'cle of this class of parasites. 



The advanced changes which take place in the different organs of the body, 

 particularly the degeneration of the bones, their increased brittleness, joint ulceration, 

 &c., are beyond our present knowledge and do not, for the present at least, admit of 

 an explanation. That a few trypanosomata located in the vaginal mucous membrane 

 can of themselves create such a disturbance, it is unreasonable to presume, and future 

 studies must be directed to this feature, with a view of determining the cause of these 

 marked changes. There is a possibility of this whole process being due to defective 

 nerve supply and located in those centres having direct control over the nutrition of 

 the animal. The extensive histological studies of Marek, however, have failed to 

 reveal such lesions and we will, therefore, have to defer any remarks in this connec- 

 tion until our knowledge in this direction is more complete. 



We have found in working with the Trypanosoma gamlnense (sleeping sickness) 

 that there is a toxine present in the blood serum which creates a disturbance when 

 injected into guinea-pigs. With sleeping sickness, however, there is little or no trouble 

 in the demonstration of the parasite, and we are led to conclude that the toxine of the 

 Trypanosoma equiperdum is much more disastrous to the growth of the organism than 

 is the case with the parasite of sleeping sickness. Further, we are led to believe 

 that it is the toxine, in cases of dourine, that to a large extent is responsible for the 

 lesions produced. 



Certain bodies have been observed in some of the preparations taken by Watson 

 and later studied by both of us, which may be trypanosomata in an involution stage. 



I cannot agree with Thiroux and Teppaz,* however, that the red granules seen 

 in the large mononuclear l;sTTiphocytes of horses (when stained with eosin and methylene 

 blue in any of its combinations), represent the remains of trypanosomata, for we have 

 observed these granules almost without exception in smears taken from the general 

 and peripheral circulation of healthy horses. (See tables I to IX given under ' Blood 

 examinations in cases of Dourine.') Another criticism of their work is ,that their 

 diagrams do not indicate the evolution spoken of in the text of their article, as the 

 trypanosoma shown within the large mononuclear cell (fig. 16, their illustrations) 

 has lost its centrosome and its undulating membrane, while the next figure presents 

 what are described as the centrosomes of a number of trypanosomata, together with a 

 portion of an undulating membrane. 



That the organisms of dourine may be taken up by the large mononuclear 

 lymphocytes, I cannot refute or substantiate, as none of our observations have included 

 such phenomena. It would appear, however, that the lymphocytes exert some action 

 inimical to the parasites, otherwise these cells would not appear in such large 

 quantities in the circulating blood of animals in a passive stage of the disease as 

 indicated by the tables appended to this report. 



PATHOLOGICAL ANATOMY OF DOUKINE. 



With the pathological anatomy of dourine I have endeavoured to make myself 

 familiar, and, therefore, will indicate the lesions usually found at autopsy. 



All of the cases upon which it has been my privilege to hold autopsies, have been 

 destroyed on account of their presenting clinical evidence of the disease, and, with 

 one or two exceptions they were of long standing. 



As a rule the general condition of an affected animal is much below normal, 

 there is little evidence of fat, the ribs dre prominent and the hip bones are easily 

 distinguished. Incision of the skin reveals the connective tissue to be of a yellowish 



• Les Trypanosomiases animales au Senegal. M. Thiroux et M. Teppaz. Annales de 

 rinstitut Pasteur, March, 1907. 



