DR. J. MURIE ON THE ORGANIZATION OF THE CAAING WHALE. 293 
oxygenated residuum in lieu of more frequent respiratory acts. With reference more 
particularly to their distribution in the limbs, Von Baer conceived the manifold sub- 
division as concurrent with paucity of movement of the members. Besides playing the 
part of great lagoons (reciprocal recipients of a circulatory overflow, as some put 
forward), Professor Turner avers, as Milne-Edwards' had already advanced, and reason- 
ably, that such subdivision distributes, equalizes, and retards the blood’s force ere 
reaching the sensitive nervous centres &c. 
I believe they are designed to execute a highly important vito-physiological process, 
which may be combined with some subsidiary mechanical adaptation as has been 
asserted. Their office is equivalent to modified blood-glands, in some way related to 
pabulum or nutrient fluid. The retia mirabilia in Cetacea and many other Mammals 
are not confined to the cerebro-spinal tract and neighbourhood of the respiratory 
apparatus, but principally follow the lines in body and limbs where the lymphatics 
and absorbents are known to obtain in the greatest profusion. Moreover, in Cetacea, 
Sirenia, Phocide, and other forms where retia are very manifest, even some birds, the 
lymphatic glands are unusually abundant and of large size; so that their intimate 
connexion with the vascular plexuses is a most presumptive conclusion. I apprehend 
that the countless divisions, subdivisions, and minute vascular osculations, by coming 
in close contact with the lymphatic system, conduces to an interchange or exudation of 
their constituents’. What further physiological process takes place I am not prepared to 
demonstrate, though inferentially I would adduce multiplication of the lymph-corpuscles ; 
a view maintained by some as respects the office of the lymphatic glands. Such a pro- 
position is applicable to many varied physiological phenomena of absorption and nutrition 
in divers animals well known to possess fully developed retia mirabilia. 
4 Lecons, Physiol. Anat. Comp. 1859, vol. iy. p. 260, 
? T conceive, as already mentioned, that there is a certain functional homology between the so-called caudal 
hearts of lower vertebrates and the Cetacean mesenteric moniliform tube of Turner. In like manner I regard 
the human so-called coceygeal gland as strictly homologous with the inferior caudal plexus of Whales &c. 
Moreover, as the vascular retia distributed throughout the body and limbs are essentially similar in constitu- 
tion, it follows they may all serve one office. As there is in the first case a manifest intermixture of plasma 
(Jones, 7. ¢.), so in the second, by absorption or otherwise, may a phase of nutrition be subserved. Abnormal 
developments of the lymphatic and vascular systems are pari passu pronounced, though not restricted to the 
aqueous and amphibious vertebrates and those that hibernate ; in them, though respiration may be checked or 
subdued, nutrition must perforce go on. Do the retia and lymph-sacs, then, supplant the necessity for frequent 
respiration, or substitute by subsidiary function a reserve force where depuration or nutritive quality of the blood 
is interfered with? 
