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316 I may not have succeeded in translating into very terse or elegant language, some of the more complex of the compound German words.—E. P. W.]

In the xxxiii. volume of the "Sitzungsberiehte der naturwiss. Classe der kais. Akademie der Wissenchaften zu Wien," I published a treatise on hearts devoid of nutritive blood-vessels. (Ueber gefässlose Herzen). I there demonstrated, by microscopical investigations, that the heart, in all the Amphibia, presents the remarkable peculiarity, that the Arteria coronaria, which arises from one of the first branches, into which the Bulbus arteriosus splits, and at some distance from the heart, supplies only the Bulbus arteriosus itself; and that not the smallest arterial branch enriches the muscular substance of the Ventriculus, or of the Atrium cordis.

I have likewise demonstrated, that the heart of Sauria, Ophidia, and Chelonia, is also partially deprived of blood-vessels; in them, the outermost layer of the muscular stratum of the heart, possesses, like all the other muscles, a capillary network, but still, the greater part of the heart-mass is entirely destitute of nutritive blood-vessels. This is the case, too, with all the osseous Fishes, while the more highly organised Rays and Sharks have, like warm-blooded animals, the coronary arteries distributed to the whole muscular coat of their hearts. In the paper, alluded to, I have stated the reason why such an apparent anomaly is, in these several cases, quite in accordance with physiological principles; and I need not further allude to the matter here. My reason for referring to it at all is that I have now met with the same exclusion of all nutritive arteries, in a different organ, and not only is the organ one of similar importance, but it also presents so constantly this state of anangia (a priv.—), that the latter becomes almost an anatomical characteristic of certain classes of Vertebrata.

The retina of all Birds, Reptiles, Amphibia and Fish, osseous and cartilaginous, contains not the slightest trace of blood-vessels, so that the vascularity of the retina occurs only in the Mammalia. I communicated a short notice of this interesting anatomical fact to the Academy of Sciences in February, which will not, however, be printed until towards the end of the year (1861), as there are many prior papers for publication. Hence, I have thought, that a note of the existence of these anangious retinas would not be without interest for the readers of the Natural History Review. I trust, that those engaged in optical inquiries, will see the importance of this discovery, for the assertion of physicists, that the blood-vessels of the retina must absorb some of the rays of light, and so cause certain