450 LYMPHATIC SYSTEM. 



anatomical characteristic of which is enlargement of lymphatic glands, 

 and the histological characteristic increase in number of the large 

 and small lymphocytes. 



(8.) A third variety, formerly regarded as simple leucaemia without 

 lymphadenitis, is myelogenic leucaemia or myelo-cythaemia, the ana- 

 tomico-pathological characteristic of which is to be found in myeloid 

 hypertrophy of the bone marrow, giving to the bone marrow on post- 

 mortem examination a puriform appearance, and in the myeloid 

 condition of the spleen. 



Histologically this variety is characterised by an absolute increase 

 in numbers of the large mono- and poly- nuclear eosinophile leucocytes. 



Symptoms. Simple lymphadenitis begins in an insidious manner, 

 and is characterised by weakness, anaemia, paleness of the mucous 

 membranes, and wasting without apparent reason, although the appe- 

 tite is preserved. It is only at a later stage that the glandular enlarge- 

 ments are discovered (adenitis), and often this discovery is not made 

 until the veterinary surgeon is called in. 



The existence of the disease is indicated by enlargement of the 

 superficial glands, and this enlargement, which may commence at any 

 point, extends along the course of the lymphatic vessels to the neigh- 

 bouring glands, until in a shorter or longer time it involves all the 

 lymphatic glands in the body. 



The enlargement of the glands is usually symmetrical, and on 

 clinical examination it is sometimes easy to detect at the outset 

 an increase in size of the retro-pharyngeal glands, the glands of the 

 neck, the prescapular glands, the glands of the flank, etc. 



Eectal exploration reveals hypertrophy of the glands of the pelvis 

 and of the sublumbar region, etc. The animals waste very rapidly, 

 and sometimes in a few months become incapable of standing. They 

 develop cachexia, and die in a state of exhaustion, with no other lesions 

 than those of lymphatic hypertrophy. Neither do they exhibit any 

 marked increase in the number of white corpuscles in the blood. 



In lympho-cythaemia the beginning of the disease is often identical 

 with that of simple lymphadenitis, the increase in the number of white 

 blood corpuscles not occurring until later. In other cjases, on the con- 

 trary, leucaemia appears first, and the enlargement of the lymphatic 

 gland follows; but what characterises this form and allows of it being 

 distinguished from myelo-cythaemia is the great increase in the number 

 of large or small lymphocytes. The development is identical with, and 

 sometimes much more rapid than, that of the preceding form. The 

 animals waste away and become anaemic an(J cachectic, dying at last 

 in a state of absolute exhaustion. 



Post-mortem examination reveals, as in the previous condition, 



