S4 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 instinct, in 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 lacuna, burrowed in the 

 parenchynae of the animal. These lacunae 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 in 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 beings 

 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 aeration. 



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 



