560 
CONTRIBUTIONS TO THE PATHOLOGY AND 
a totally different nature : close observation, however, I have no 
doubt, will enable this very talented gentlemen to discover its true 
nature, and place it in that position to which it justly belongs. 
Again, in The VETERINARIAN for 1845, some well-marked cases 
are given by my friend and excellent practitioner, Mr. James 
Moore, V.S., of Manchester; which, together with two other papers 
in the Veterinary Record for 1848, one by Mr. Mannington, V.S., 
of Brighton, and the other by Mr. Boag, V.S., of Kelso, are all with 
which I am acquainted, or remember to have seen furnished to the 
readers of The VETERINARIAN and the Record during the last 
ten years. In the remarks, therefore, which I have to offer re- 
specting Purpura, I propose, in the first place, to consider the nature 
of the disease ; secondly, its causes, predisposing and exciting ; 
thirdly, its varieties; fourthly, its complications ; fifthly, its prog- 
nosis; and, sixthly, its duration. 
Nature of Purpura. — The pathological definition which Dr. 
Copland gives of Purpura, in part 13 of his Dictionary of Practical 
Medicine, is as follows : — “ Depressed organic nervous energy , 
giving vise to impaired tone of the capillaries , especially of the 
mucous and cutaneous surfaces, and to diminished crasis of the 
blood, thereby permitting the passive exudation of this fluid.” 
John Field defines it to be, 1st, “an increased tenuity of the blood; 
2d, dilatation of the mouths of the capillaries, admitting natural 
blood to pass through them ; 3d, tenderness of the coats of the 
vessels, giving way from the ordinary impetus of the blood ; 4th, 
increased impetus, rupturing healthy vessels ; 5th, obstruction in 
the capillaries ; 6th, two or more of these causes combined. Still, 
the universality of the disease does not allow,” he further remarks, 
“ of the proper explanation of the phenomena from either of the 
above causes, and the more rational mode of explaining it seems 
that which refers to an alteration in the condition and vital proper- 
ties of the blood.” I cannot say, however, that I am satisfied with 
either of the above definitions. When applied with reference to 
this disease in the horse, they appear to me to want comprehen- 
siveness; particularly the latter. To define any thing very accu- 
rately, and at the same time comprehensively, especially when the 
subject of definition is in itself intricate, is, I know, a task of con- 
siderable difficulty ; in short, to fully define a disease is a matter 
which can only be done by telling all about it; and so far as any 
thing remains untold which can be told respecting it, so far is the 
definition incomplete. 
Purpura, says Dr. Copland, is a disease “ intimately related to 
the hcemorrhages on the one hand, and to scurvy on the other ; 
being intermediate between them, or forming the link which con- 
nects them ; certain cases hardly admitting of any distinction be* 
