1866. ] Loology and Animal Physiology. 441 
very long and tremulous, and but slightly oblique, while the descend- 
ing is abrupt and nearly perpendicular. The application and value 
of the instrument will be apparent from these remarks. 
Dr. Edward Schunck has communicated a paper to the Royal 
Society “On the Colouring and Extractive Matters of Urine.” He is 
led by his experiments to conclude that human urine contains at 
least two peculiar colourmg matters,—one soluble in alcohol and 
ether, while the other is soluble in alcohol but not in ether. The 
existence of a third insoluble extractive matter appears very 
doubtful. 
Tn our last “ Chronicle” we noticed the researches of M. E. Alix, 
on the “ Parturition of the Marsupials,” in which he attributed the 
discovery of the mode of performance of this function to M. Jules 
Verreaux, and also on anatomical grounds supported Sir Everard 
Home’s views in opposition to those of Cuvier and Owen. Prof. 
Owen has now sent a communication to the Academy of Sciences of 
Paris, in which he overthrows the claims of M. Alix to a discovery, 
and at the same time reviews his own labours on the question at 
issue, and gives an account of the parturition of a Macropus mayor, 
which he had isolated at the Zoological Society’s Gardens for some 
time, several years since. It appears that M. Alix had only con- 
sulted Prof. Owen’s researches through the medium of a Cyclopedia. 
Dr. Drosier, of Caius College, Cambridge, has lately been making 
some observations on the Functions of the Air-cells and the Mechan- 
ism of Respiration in Birds. He remarks that several of the 
commonly received views are quite untenable, such as that the air- 
cells are intended to assist in supporting the bird in flight by 
rendering it lighter, in consequence of the rarefaction of the air in 
_ the air-cells and the hollow bones; and again, that the air-cells are 
a sort of second respiratory apparatus, so that birds may be 
described, as they were by Cuvier, as animals having a double respir- 
ation. In disproof of these views, Dr. Drosier has shown that a 
pigeon weighing ten ounces would have its weight in air diminished 
by less than one grain, in consequence of the rarefaction of the air 
in its air-sacs and hollow bones ; so that the floating-power result- 
ing from such rarefaction would be almost inappreciable. Again, 
the air-cells are so sparsely supplied with vessels, that they can offer 
but very little blood for oxidation. It has been frequently sup- 
posed that air passes from the air-sacs into the cavities of the 
eritoneum and pericardium, and even between the muscles. This 
1s, however, an error, as was shown by Guillot and Sappey. Dr. 
Drosier conceives that the air-sacs are simply appendages to the 
lungs for the reception of air. The respiration of birds is necessarily 
very rapid and vigorous, and at the same time the lungs are small. 
The large quantity of air inhaled at a respiration is received into 
the air-sacs, and by the alternate contraction and expansion of the 
2a2 
