DB. J. MUEIE ON THE ORGANIZATION OF THE CAAING WHALE. 293 



oxygenated residuum in lieu of more frequent respiratory acts. AVith 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 overflo'^, 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, Phocidse, 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 otfice 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. 



' Legons, Physiol. Anat. Comp. 1859, vol. iv. p. 260. 



° I 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 coccygeal 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 foUows they may all serve one office. As there is in the first case a manifest intermixture of plasma 

 (Jones, I. c), 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 ? 



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