The blood, which is deep red, appears to flow into the extreme end of this organ in a continuous stream, but is forced out at each contraction from the other aperture in an interrupted current. The absence of any re gurgitation, at the further end of the heart, would suggest the presence of some valvular apparatus there situate. The jet of blood, sent forward at each contraction, may be beautifully seen by holding up the tail of the eel to the light ; it is seen as a regular, ar terial, per-saltum, jet, passing along the vessel in front of the heart, which, in the intervals of each contraction, is empty: as Dr. Hall expresses it, the blood is " propelled with great velocity, at first with the appearance of successive drops."1- This per saltum cur rent only exists a short distance, and gradu ally degererates into a continuous, venous, stream. When the parts are submitted to low magnifying power, I have observed that at each systole of the heart the veins at the distal extremity of the organ are vio lently tugged in the longitudinal direction (produced by the shortening of the heart in its contracted state), and this exists as far as several ramifications from the heart (d' d').
A movement in the opposite direction takes place at the diastole, which is doubtless as sisted by the elasticity of the vessels restoring them to their former length. This circum stance, moreover, proves the complete con tinuity of structure of this organ with the small vessels which furnish the blood upon which it contracts.
I have seen this best when the tail has been cut from the body,— the bloodless heart still going on contracting.
I have failed altogether to find any lym phatics going to this pulsating organ ; and the facts which I have already adduced, that it receives blood from behind, and transmits it forwards ; the large aggregate quantity of fluid which it propels in a given time ; the rhyth mical tension of the capillary veins, attached to the distal end, at each contraction, as well as the apparent absence of lymphatics, seem to prove that it is a blood, and not a lymph, heart.