694 
ON Tim LACTEAL AND 
called red, or cold-blooded , as fishes and reptiles*, we find that, 
although they possess red blood, yet the greater portion of their 
bodies are supported by blood of a transparent or white colour ; 
blood of a red colour existing principally in those parts of the 
circulation nearest to the centre of the system, as the liver, 
heart, &c. 
On the other hand, as we proceed to the more complicated 
part of the creation, such as are commonly called warm-blooded, 
as them mammalia and man, we find that they possess red and 
white blood likewise, but that the red parts of their bodies by 
far exceed those of the whi t e ones. In the former instance, we 
include all the strong and more powerful parts of the body, as the 
muscles, skin, mucous membranes, some portions of the larger 
bones, &c. ; in short, all the various parts of the body which de¬ 
rive their support from blood of a red colour : while, in the lat¬ 
ter instance, we include all the white parts of the body, which 
Galen and the ancients distinguished by the name of spermatic , 
as the tendons, ligaments, cartilages; also the serous, cellular, 
and synovial membranes ; likewise the greatest portion of the 
osseous system ; in short, all the various parts of the body which 
are supported by white or transparent blood. 
' Most of these white parts just mentioned were considered as 
not possessing any bloodvessels, and, of course, as not to be 
nourished by the blood, until, about the year 1700, Ruyssch, the 
celebrated anatomist, first demonstrated, by his minute injections, 
that even the compactest bones, cartilages, tendons , ligaments, the 
finest membranes, &c., are all furnished with arteries, in a similar 
manner to those of the red parts ; and, of course, that they de¬ 
rive their nourishment from, and are supported by, white or 
transparent blood. 
Now, that we are fully aware that both the white and red 
parts of the living body are nourished and supported by blood, 
and that the blood in the higher orders of the animal creation is 
not only distributed to these different parts of a red, but also of 
a white colour, we must necessarily conclude that this 
transparent or white-coloured blood, which is for the purpose of 
nourishing and supporting all the inferior parts of those animals 
which possess also blood of a red colour, is also of a similar na¬ 
ture to the transparent or colourless blood, which belongs to, 
and supports, the whole system of all those animals that are 
* Mr. Hewson was one of (lie first who investigated and described the 
lymphatic vessels in fishes and amphibious animals.—See Philosophical 
Transactions , 1769. 
Mr. Hunter and Hewson were also the first who investigated the lym¬ 
phatic vessels in birds.—Sec Hewson, Philosophical Transactions, 1768. 
