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Dr. John Davy on the Bones of Birds. [Dec. 6, 



4. Of the humerus of a goose hatched in the spring, weighing on the 

 2nd of November nine pounds, the canal was found full of air, with the 

 exception of its inferior one-third ; this contained marrow rich in oil. In 

 one of several portions of it submitted to the microscope, a red vessel was 

 seen containing granules and oil- globules. In one direction it ended 

 abruptly, as if torn ; in the other it was lost, as it were, by diffusion into, or 

 blending with the cells of the medullary tissue. The upper portion of the 

 marrow, it may be remarked, where it came in contact with the air, had, 

 as in some other specimens, a rounded well-defined surface. In this 

 instance no large blood-vessels were found in any part of the bone ; and on 

 the delicate membrane connecting the trabeculse of the cancellated struc- 

 ture, only a very few delicate vessels of a florid hue were to be seen. 



5. Of a fifth, also hatched in the spring, when examined on the 20th 

 of November, the humeri, like those of the last but one, were found to 

 contain only air. Their lining membrane was very vascular and partially 

 varicose. 



V. Of the Common BucTc. — Of a young drake hatched on the 26th of 

 April, which when weighed on the 13th of August was four pounds, the 

 humeri sank in water. They containad a light reddish marrow, and were 

 entirely destitute of air. 



2. Of two ducks of the same brood as the drake, the humeri, examined 

 on the 15th of August, sank in water. Two-thirds of each were filled with 

 marrow ; one-third, the upper portion, with dark blood, seemingly in 

 varicose vessels, which were connected with a light-coloured delicate mem- 

 brane. 



3. Of a duck, little more then one year old, the humeri contained only 

 air. 



VI. Of the Red Grouse. — Of one, which on the 12fch of August was 

 not fully fledged (it was shot for examination), the humeri contained air, 

 the femora marrow. 



2. Of another more advanced, shot on the 31st of August, weighing a 

 pound and a quarter, the humeri contained air, the femora a little marrow, 

 but more air, the former inferiorly. 



3. Of a third, shot on the 28th of August, which weighed 8770 grs., 

 the humeri were hollow, the femora partially so, a little reddish marrow 

 only remaining, and this in their inferior extremity. 



4. Of one shot on the 27th of August, which weighed 11,856 grs., and 

 which, judging from its plumage, was probably a spring bird, both the 

 femora and humeri swam in water and were free from any trace of marrow. 

 The lining membrane of the cavities of the femora was beautifully vascular, 

 the vessels of a florid hue from the well-aerated blood which they contained. 

 The lining membrane of the humeri was similarly vascular, but in a less 

 strongly marked manner. 



VII. Of the Rook. — Of a young one not quite capable of flight, shot 

 on the 11th of May, and which then weighed 6132 grs., the humeri sank 



