626 MR. youatt’s veterinary lectures. 
rate enlargement, but the whole of the cranium seems to be forced 
outward and with strange deformity. This, however, is a very 
rare disease. 
Hydrocephalus, if not congenital, seldom attacks the young 
Animal .—I never saw a casein which water in the head accumu¬ 
lated in a young animal that was born healthy, nor do I believe 
that there is one upon record. This is very singular, considering 
how many infants and children fall victims to this disease. It is 
a circumstance for which I am unable to account, except that the 
different state of the skull in the infant and the quadruped may 
exert considerable influence on the progress, if not the origin, of 
the disease. In the infant none of the bones of the skull are 
perfectly formed. In some of them the process of ossification 
has scarcely commenced. Few or none of the sutures are 
closed, and the fontanel or chasm at the meeting of the coronal 
and sagittal sutures long continues open. If, from certain 
causes, inflammation should be established in any part of the 
brain or its membranes, and the effusion from the exhalent 
vessels consequent on this should commence, the cavity of the 
cranium readily enlarges as the fluid pours out, and offers little 
resistance to its accumulation. In the quadruped, however, ex¬ 
posed to dangers from which the helplessness of the infant 
exempts him, the brain has a firmer covering; the process of 
ossification is much farther advanced; the sutures have closed; 
the fontanel never had existence, or is obliterated; the cranial 
cavity is incapable of enlargement, and when the process of effu¬ 
sion commences, that pressure on the exhalent vessels takes 
place which is the most effectual restraint on their inordinate 
action. 
Some medical practitioners have resorted to compression in 
chronic hydrocephalus, and they have imagined with advantage ; 
but the grand difficulty has consisted in rendering that pressure 
perfectly equable, and being enabled to apply it before the habit 
of effusion was established, and when alone it could be arrested 
with safety, or arrested at all. Nature has here contrived a 
uniform and seemingly effectual resistance to the accumulation 
of the fluid. 
The diminished size of the brain itself in the quadruped ; the 
preponderance of that part of it, the medullary substance, which, 
although it may suffer from the pressure, is little concerned in 
the production of the fluid; and also the lack of the cortical or 
cineritious portion, in or about which the effusion takes place,— 
these things may have effect in preventing in the quadruped a 
disease so fatal in the human being. 
Accumulation of Fluid in the Ventricles. —In the adult animal. 
