DISEASES OF THE LYMPHATIC TISSUES 117 
Pinnepedia 4. Chronic changes are mentioned 43 times 
as follows : Primates 7, Carnivora 19, Ungulata 14, Mar- 
supialia 1, and Pinnepedia 2. This great proportion 
among the Carnivora does not indicate that they have 
more lymphatic structures for such an advantage is prob- 
ably possessed by the Ungulata, but perhaps should be 
interpreted as an evidence for this order of the ready 
response to irritation on the part of the tissues in ques- 
tion. They probably suffer more, as we shall see later, with 
inflammation affecting drainage tracts. The hyperplasias 
or inflammations included in the figures above most often 
accompany gastroenteritis, pulmonary diseases or long 
standing infectious processes such as arthritis, while 
there are also lymphatic enlargements both local and 
general, associated with skeletal degenerations (rachitis- 
osteomalacia) and with thyroid disease. The former may 
be described as lymphadenitis, the latter as lym- 
phatic hyperplasia. 
Unlike lymphadenitis, a condition associated mth 
some definite infectious or toxic cause, systemic hyper- 
plasia of the lymphatic tissue may be apparently primary 
and causeless. In a pathological and clinical sense alike 
these hyperplasias are protean in their manifestation, 
making a satisfactory classification extremely difficult. 
For our purposes they are divisible into acute and 
chronic, associated with an increased number of circu- 
lating lymphocytes and mthout such a lymphocytosis. 
The first, acute systemic lymphatic hyperplasia, is 
known in man as status thymico-lymphaticus, a well 
recognized condition chiefly encountered in youthful 
males having some of the stigmata of the opposite sex. 
There is no record, nor have I any recollection of a patho- 
logical state in a wild animal comparable to this condition. 
If acute generalized lymph node increase be associated 
with lymphocytosis, acute lymphatic leucemia exists ; 
there is no case in our records. Chronic enlargement of 
lymph nodes with increase of circulating mononuclears is 
