the Ornithorliynchus paradoxus. 95 
conduct it to the various organs and tissues of the body. 
In many of the Entozoa , Polihypithera , and infusory 
animalcules, the alimentary canal is disposed in avascular 
form through the substance of the body : by this arrange¬ 
ment the digestive apparatus serves the double function 
of digestion, and that of a vascular system, at the same 
time. 
In some of the infusory animalcules, and vesicular 
Entozoa , no visible digestive cavity exists, and con¬ 
sequently no vascular system : hence the surface of the 
body seems to serve the office of a stomach, and the 
nutritious matter to pass into the substance of their 
homogeneous bodies by endosmose. 
There appears to be strong analogy betwixt the various 
kinds of nutritious fluid both of plants and animals ; 
for example, we find in the sap innumerable globules 
floating in a clear fluid. It is derived from foreign 
matter, and converted by the vital energies of the plant 
into its own likeness. The same physical character 
is seen in animals, and corresponding physiological 
functions are in operation. 
The nutritious fluids of the various classes of animals 
from sponges up to man, exhibit the same essential 
characters, and serve the same purposes in the monad as 
in the most intellectual individual of our race. 
The nutritious fluid in the invertebrate classes is of 
various colours ; in some, as in the class of Annelides the 
blood is red, as in the vertebrate classes. In many 
Mollusca it is colourless; in others, bluish. I 11 the 
Planorbis it is of a very deep blue. In many insects 
it is yellow, in others colourless, but more frequently 
brown. 
If we examine with a microscope a drop of blood spread 
in a thin stratum over a piece of glass, we observe a 
transparent colourless liquid, in which are suspended in- 
