680 PEOEESSOR T. WHARTON JONES ON THE CATTDAL HEAET OE THE EEL. 
Dr. Marshall Hall would have been inadequate for the performance of the function he 
attributed to the caudal heart of the eel. 
Though the late Professor Johannes Muller, in his paper in Poggendorff’s ‘ Annalen’ 
for 1832 above quoted, remarks that “ further observations must teach whether the 
function of this organ (the caudal heart in the eel, the discovery of which by Dr. Mar- 
shall Hall he had just learned from the 698th Number of Froriep’s ‘ Ndtizen ’) is to 
drive the lymph of the tail into the end of the caudal vein,” he did not, in his paper on 
the lymphatic hearts of Amphibia, question Dr. Marshall Hall’s representation of it 
as a blood-heart. 
In the paper referred to, which was published in the Philosophical Transactions for 
1833, and is entitled, “ On the Existence of four distinct Hearts, having regular pulsa- 
tions, connected with the Lymphatic System in certain Amphibious Animals,” Professor 
Muller, then of Bonn, makes the following statement: — “ In the vascular system of the 
blood, there certainly are particular places, besides the heart, which are capable of con- 
tractions ; as, for example, the bulbus aortse in fishes and batrachia, the venae cavee where 
they enter the atrium, and the pulsating organ discovered by Dr. Marshall Hall in the 
eel at the end of the vena caudalis, where that organ receives the branches of the extre- 
mity of the tail and conducts its blood into the vena caudalis. But organs of pulsation 
in the lymphatic system have hitherto been altogether unknown.” 
Again, Professor Muller, in his ‘Archivfiir Anatomie und Physiologic’ for 1842, 
p. 477, published a paper entitled “ Bemerkungen uber eigen thiimliche Herzen des 
Arterien- und Venen-Systems,” in which he says, “To the heart-like contractile parts of 
the blood-vascular system the following structures belong : — 
“ A. To the venous system : 
« 1 . * * * * * 
“ 2. The heart of the caudal vein of the eel. The pulsation at this place was seen by 
Leeuwenhoek, who, however, did not examine into the nature of the thing. Marshall 
Hall is the discoverer of this heart.” 
I shall return to the claim set up for Leeuwenhoek, as it has been reproduced in a 
more decided manner by Professor Milne-Edwards of Paris. 
In Muller’s ‘ Archiv’ for 1843, p. 224, Professor Hyrtl, at that time of Prague, but 
now of Vienna, has a paper entitled “ Ueber die Caudal- und Kopf-Sinuse der Fische, 
und das damit zusammenhangende Seitengefass-System,” in which he refers to Dr. 
Marshall Hall’s discovery of the caudal heart of the eel, and describes his own exami- 
nation of the pulsations of the organ with the naked eye, in the tail of a large eel held 
against the window-pane, but says nothing in opposition to Dr. Marshall Hall’s 
opinion of the nature of the organ. 
Professor Milne-Edwards, in his “ Lemons sur la Physiologie et l’Anatomie comparee,” 
vol. iv. (Paris 1859) p. 476, correctly views the pulsating organ in the eel’s tail as a 
lymphatic heart, but adduces no facts, either anatomical or physiological, to prove that 
the organ is of this nature. He merely refers to Professor Muller as having recognized 
the organ to be a lymphatic heart. 
