LIVERPOOL VETERINARY MEDICAL ASSOCIATION. ] 35 
were alluded to by Mr. Fleming to account for the symptoms 
observed in the disease under consideration, I thought it better 
to show that on them even there was very great difference ol 
opinion, and that anaemia does not play such a role in the pro¬ 
duction of these conditions and diseases as has hitherto been 
assigned to it. And further, that granting anaemia to be the 
physiological condition in the disease, the anatomical peculiarity 
existing in the cranial blood-vessels of ruminants contributed 
nothing towards its production; nay, rather that it tends to pre¬ 
vent it by equalising the circulation, and thus preventing conges¬ 
tion of the organ and its consequences. 
It is very difficult indeed to see how it could bring about 
anaemia in the way indicated by Mr. Fleming, nor does he make 
it very evident how anaemia occurs at all through this arrange¬ 
ment. 
The following, he says, “ seems to be the result of the peculiar 
distribution of the vessels :—1st. The circulation of arterial 
blood to the brain is very uniform. 2nd. Irregular pressure in 
the aortic system cannot easily, and then only slowly, be trans¬ 
mitted to the arteries of the brain. 
“Now, however, Bidder’s experiments have shown that sudden 
increase of blood pressure does not produce any comatose 
symptoms, but that these always set in if the increased pressure is 
of any duration. Under these circumstances, brain oedema is 
much more likely to set in than if the blood pressure were to 
disappear quickly/’ 
Now the question to be asked and answered here is, Where 
does this increased and prolonged blood pressure take its rise, 
and how is it sustained ? 
It cannot certainly be in this rete mirabile, or an artery 
suddenly dividing, without altering its normal dichotomous dis¬ 
position, and then gathering itself up again. The effect of this 
is evidently to slacken and slow the circulation, and if the vis a 
tergo be removed or weakened, this peculiar arrangement will 
respond in accordance with the constitution of all arteries, and 
which is but a physiological result of the struggle between the 
two elements composing the tube, the elastic and the muscular. 
The increased pressure must take its rise from the heart’s 
hyperplasia, the increased quantity of blood returned to the cir¬ 
culation, and the parturient state conditions present in a greater 
or less degree in all animals. 
Unless we suppose, for he does not avow it, he believes that 
the amount of blood or fluid circulating in the brain is an un¬ 
varying quantity, and that in consequence of this dilatation or 
diverticulum on the carotids of ruminants the blood is held back 
for a time, and rushes into the soft brain tissue after the vis a 
