34 BRITISH MARINE TESTACEOUS MOLLUSCA: 
its concomitant nervous and muscular influence, that produces 
the motions which are the tests of vitality. I may state that 
Lamarck does not admit the distinction of intelligence and 
instinct ; he very justly considers the different degrees of what 
is called imstinct, mm animals, as only subdued intelligences 
consequent on their imperfect organs, when compared with 
the highest standard—man.” 
The contents of the visceral cavities or walled ducts, whether 
they consist of solid food or chyliferous fluid, have precisely 
the same function as in the higher animals, that of susten- 
tation; and whatever may be the nature of the blood fluids 
which fill the vascular apparatus of every living being, and all 
have one, we think they ought to be termed the true blood, as 
it always flows in parietal contractile tubes, arteries, or veins, 
and never in excavations called J/acune, burrowed in the 
parenchyme of the animal. These /acune do not apply to 
visceral matters ; they are simply aquiferous canals to give tone 
to the various muscular organs of the Invertebrata, and not 
for the circulation of blood. When we say that a vascular 
circulating and respiratory system exists im the monad as well 
as in man, we admit that these organs are often simplified to 
the extent of the requirements of the various tribes. We do 
not contend that the elaborate structure of the higher inverte- 
brates obtains in the radiate organisms; but we think that 
if there be not a heart receiving blood by auricles, and con- 
veying it by arteries and veins through a general circulatory 
and respiratory apparatus, there are in the simplest beimgs 
equivalent conditions, and that the typical heart of systole 
and diastole agency is often represented in the vascular me- 
chanism by receiving from muscular contractibility and relaxa- 
tion a power which gives a sufficient impulse to the blood to 
secure its enrichment and aération. 
And further, with respect to the circulatory apparatus of 
these inferior organisms, though its tubes and cavities may 
not have the gradual decrease and increase of the arteries and 
veins as in the higher animals, nor consist of an afferent and 
efferent set of vessels, we consider that the substitutes of these 
organs are sufficiently supported by analogy, if the blood is 
