CHYLAQUEOUS FLUID OF INVERTEBRATE ANIMALS. (]05 
impressed with the Jirst impulses of zoo-chemistry before it is fitted to enter into 
combination with the vital fluid. The facility with which the most depressed forms 
of life appropriate and vitalize a complex inorganic liquid, may be signalized as a 
true badge of zoological inferiority. When ejected from the body, as it often is, at 
the will of the animal, the vital fluid is renewed, organically, and corpuscles grow in 
it with incredible rapidity. The entire contents of the system of the true-blood can in 
no single instance be withdrawn from its vessels (except in very small quantities) 
compatibly with the preservation of life. Hence another fundamental difference be- 
tween the physiological history of the blood-system and that of the chylaqueous. 
How significantly that of the latter speaks as to the ‘‘simplicity” of the living 
organism in those orders of which it constitutes the exclusive means of nutrition ! 
Echinodermata. — Physiologists, from Tiedemann to Muller, commonly describe in 
this family three distinct systems of fluids ; that, 1st, of the general cavity of the body; 
that, 2ndly, of the feet and water-canals ; and that, 3rdly, of the blood-proper. The 
doctrine which maintains the perfect independence of these three orders of fluids, is 
advocated by these two illustrious anatomists. Facts will now be adduced which 
render it probable that these three apparently independent systems constitute really 
only a single indivisible fluid-system. They will be found to warrant no other con- 
clusion than that in Echinoderms the system of the blood-proper is so rudimentarily 
formed, that its contents, by some means and in some undetermined manner, commu- 
nicate and mingle with those of the general cavity of the body, since in every histolo- 
gical character the morphous elements and chemical compositions of the two fluids 
prove, under every mode of inquiry, to be identical. From the same method of 
examination, the inference is confidently drawn that the contents of the vascular 
system of the feet Das Wassergefasssystem ” of Muller and Tiedemann) are iden- 
tical, chemically and histologically, with those of the visceral cavity. But, though 
rudimentary, the blood-proper system in the Echinoderms does exist. As regards its 
central channels, it is easy, by injection and inflation, to verify the descriptive state- 
ments of Tiedemann and Muller. 
It is important to the purport of this memoir, to ascertain the sentiments of 
Muller with reference to the character and distribution of the blood-vessels in 
the Holothuridse, to which more especially he has dedicated his recent studies, since, 
as these genera stand high in the Echinodermal scale, what is true of them must 
a fortiori be true of the lowest families of the class. — “ Jedenfalls iniissen die Blut- 
gefasse zu den Korperwiinden aus dem Innern des Thiers denselben Weg nehrnen, 
w'ie die Nerven und die Wassercanale, namlich durch den Gabelfortsatz am obern 
Rande von je fiinf Stucken des Kalkringes der Holothurien oder durch die fiinf 
Stiicken mit Lochern bei den Synapten. Dies sind, wie es scheint, die einzigen Durch- 
gange vom Innern zu den Kbrperwanden. An den Gekrosen der Holothurien, konnte 
ich keine Verbindungen der Korpervviinde und Eingew’eide durch Blutgefasse wahr- 
nehrnen.” t 
4 I 2 
