ANATOMY AND PHYSIOLOGY OF THE HORSe’s FOOT. 599 
in which the stream flowing into the multitude of channels 
before it, like water through the rose of a watering can, 
rushes with all the more precipitancy as the pressure of the 
fluid is more considerable. 
Another feature in the remarkable disposition of the 
arteries in the foot has been noticed to consist in the 
functional unity that exists between certain parts of that 
region which are very dissimilar in structure, such as the 
pedal bone and its envelope ; while, again, these parts, nor- 
mally closely united, are yet to all intents and purposes 
isolated, and, through this anastomosing, continue to live in- 
dependently and as if they had no connection. These appa- 
rently contradictory properties have been illustrated in the 
following manner, and the circumstance is worth noting from 
its bearings upon the physiology and surgery of this organ. 
The third phalanx and its enveloping membranes (to be pre- 
sently described) are so intimately related by arteries passing 
to and from them, that the arterial circulation may be said 
to be common to both. On the one hand, the divisions and 
subdivisions of the plantar artery escape from the interior of 
that bone by ascending and descending branches which spread 
over its surface and into its covering ; while, on the other 
hand, the vessels that ascend from the network around the 
coronet also weave themselves into a mesh over that surface, 
and pass into the bone to meet emerging divisions from the 
plantar artery; at the same time, the divisions of the artery 
of the plantar cushion establish communications with others 
from the artery that courses along the lower convex margin 
of the bone (the circumflex), which vessel again is only formed 
by the descending ramifications of the plantar artery. From 
these divergences and communications between the nutritive 
vessels of the foot, there result a very complicated superficial 
and a deep network, in which are mixed up, in order to form a 
continuous whole, the terminating branches of those arteries 
that appear at first sight to be specially destined either to the 
bone or its membranes. In this way there is established a 
complete functional solidarity between them. 
Nevertheless, and notwithstanding this complexity of union, 
the parts composing this organ have each a vascular appa- 
ratus or system so developed that they can live and act in 
complete independence. Should the marvellous array of 
structures covering the anterior and lateral aspects of the 
bone, and known as the vascular laminaj, be entirely isolated 
from the bony surface to which it is attached by its subjacent 
network, it would still continue to be supplied by the ascend- 
ing twigs from the coronary circle; and if separated from 
