370 ON CALCULI, AND THE MODE OF 
‘ Throughout nature, air, in whatever manner concerned, .seems- 
to be indispensable to the support of life. 
In order that the seeds of plants should produce and perfect 
their respective kinds, it is necessary that their shoots should rise 
to the surface of the earth, to enjoy the benefit of the air. 
The instant animation commences, the communication of air is 
begun. Air is conveyed from the blood of the mother through 
the placenta in the mammalia ; and, to meet the peculiar process 
of reproduction in oviparous reptiles or fishes, a system is con¬ 
structed for causing air to have access to the receptacles where 
the eggs are deposited. The proof of the necessity of air in such 
cases is, that without air no incubation can be effectual. 
‘‘ Fishes'^, which deposit their eggs in water that contains only 
a limited portion of air, make combinations which would seem 
almost the result of scientific knowledge or reason, though 
depending upon a more unerring principle, their instinct for 
preserving their offspring. 
- Those fishes that spawn in spring or the beginning of summer, 
and which inhabit deep and still waters, as the carp, bream, 
pike, &.C., deposit their eggs upon aquatic vegetables, which, by 
the influence of the solar light, constantly preserve the water in 
a state of aeration. The trout, salmon, hucho, &c., which spawn 
in the beginning or end of winter, and which inhabit rivers fed 
by cold and rapid streams which descend from the mountains, 
deposit their eggs in shallows, on heaps of gravel, as near as pos¬ 
sible to the source of the stream, where the water is fully com¬ 
bined with air; and to accomplish this purpose they travel for 
hundreds of miles against the current, and leap over cataracts 
and dams: thus the salmon ascends by the Rhone and the Aar 
to the glaciers of Switzerland, the hucho by the Danube, the 
Isar and the Save, passing through the lakes of Tyrol and Styria, 
to the higher torrents of the Noric and Julian Alps.'" 
[To be continued.] 
ON CALCULI, AND THE MODE OF REMOVING THEM, 
IN DOMESTIC ANIMALS. 
Bj/ Mr, Dick, F.»S., Edinburgh. 
In No. 16, of ‘‘The Journal of Agriculture," I gave an ac¬ 
count of a case of calculus, which was communicated to me by 
Mr. Pope, of Tarvis, Aberdeenshire, detailing the removal of 
the calculus, which in its broken state weighed eight ounces. 
* The Last Days of a Philosopher, by Sir H. Davy, Bart. 
