 Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in...  Gentleman's Magazine and Historical Review - Page 821883Affichage du livre entier - À propos de ce livre
 | 1909 - 844 pages
...abounded in profusion, but in Paraguay itself they had become extinct. This was caused by the existence in Paraguay of a certain fly, which lays its eggs in the navels of these animals and so produces disease and death. There do not appear to be enough parasitic insects to keep down... | |
 | 1866 - 808 pages
...have ever run wild, though they swarm southward and northward in a feral state ; and Azara and Rengger have shown that this is caused by the greater number...must be habitually checked by some means, probably by birds. Hence if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts... | |
 | 1860 - 976 pages
...have ever run wild, though they swarm southward and northward in a feral state ; and Azara and Rengger have shown that this is caused by the greater number...must be habitually checked by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts... | |
 | Richard Holt Hutton, Walter Bagehot - 1860 - 556 pages
...and northward, in a feral state ; and this limitation is due to the greater abundance in that area of a certain fly, which lays its eggs in the navels...these flies, numerous as they are, must be habitually kept in check by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers... | |
 | 1860 - 564 pages
...and northward, in a feral state ; and this limitation is due to the greater abundance in that area of a certain fly, which lays its eggs in the navels...these flies, numerous as they are, must be habitually kept in check by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers... | |
 | Charles Darwin - 1861 - 472 pages
...ever run wild, though they swarm, southward and northward in a feral state ; and Azara and Rengger have shown that this is caused by the greater number...must be habitually checked by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts... | |
 | Charles Darwin - 1864 - 472 pages
...have ever run wild, though they swarm southward and northward in a feral state ; and Azara and Eengger have shown that this is caused by the greater number...must be habitually checked by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts... | |
 | Charles Darwin - 1866 - 668 pages
...have ever run wild, though they swarm southward and northward in a feral state ; and Azara and Rengger have shown that this is caused by the greater number...habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic... | |
 | 1906 - 960 pages
...northward in a feral state; and Azara and Rengger have shown that this is caused by the greater numbers, in Paraguay, of a certain fly which lays its eggs...habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic... | |
 | Norfolk and Norwich Naturalists' Society - 1884 - 820 pages
...Azara and Kengger have shown that tin's is caused by the greater number in Paraguay of a certain By which lays its eggs in the navels of these animals when first bom. The increase of these Hies, numerous as they are, must be habitually checked by some means, probably... | |
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