Page:Popular Science Monthly Volume 12.djvu/778

From Wikisource
Jump to: navigation, search
This page has been validated.
758
THE POPULAR SCIENCE MONTHLY.

long! It was certainly gigantic enough to entirely disprove the theory, generally accepted, that the elephant is as large as any animal can be that moves upon the land, for the bulk of this reptile must have been at least three times that of any known Proboscidian.

Among the other Dinosaurs described in this paper is Morosaurus impar, another herbivore belonging to the same family, and about twenty-five feet in length, and Creosaurus atrox, its carnivorous enemy, nearly as large, each representing a new genus. Two small species, belonging to the new genus Laosaurus, are also described. The large herbivorous Dinosaurs, from the American Jurassic, represent, according to Prof. Marsh, a well-marked family, the Atlantosauridæ, which have but three or four vertebræ in the sacrum, five well-developed digits in each foot, and the hind-feet ungulate and plantigrade—characters not before found in Dinosaurs.

 

Trees and Health.—Certain observations made by a correspondent of the Chemical News are deserving of the attention of sanitarians. According to him, the cantonment of Goruckpoor, in Northwest India, though situated near the forest and in the neighborhood of a large swamp, was thirty years ago considered a healthy station. A large grove of mango-trees existed between the swamp and the station. For some reason this grove was cut down, and the station became unhealthy. Again, the civil station of Futtehpoor is situated between Allahabad and Cawnpoor, in an arid plain, but near a pretty extensive marsh. This place was considered extremely unhealthy, until the magistrate planted between the station and the swamp a belt of quick-growning babool-trees. As the trees grew, the place became much less unhealthy. In these two cases the trees appear to have acted as a screen or filter, protecting the population from the effects of the malaria generated in the swamps. It may be added that it would be difficult to find trees more dissimilar in foliage than the mango and the babool. "Is it not probable," asks the author, "that where beneficial effects have followed the planting of the eucalyptus, the same may be due as much to the screen which the plantation has interposed, as to any peculiar action of, or exhalation from, the leaves or stem of the tree?" Referring to the changes produced, as regards salubrity, at the Trappist monastery of Tre Fontane, near Rome, which changes have been ascribed to the peculiar virtues of the eucalyptus, the author calls attention to the fact that the deep ploughing of the soil and the removal of seven hundred cart-loads of human bones from the precincts of the monastery may perhaps be credited with some share in producing the change. So, too, the eucalyptus-trees may have served, in this case also, as a screen.

 

Carnivorous Plants.—Mr. Francis Darwin, in a paper entitled “The Nutrition of Drosera rotundifolia” describes a series of experiments made by himself to determine whether or not insectivorous plants profit by their carnivorous habits. With this object two hundred plants of Drosera rotundifolia were transplanted (June 12, 1877) and cultivated in six soup-plates filled with moss during the rest of the summer. The area of each plate was equally divided by a low wooden partition, one side being destined for the plants to be fed with meat, the other for those to be starved. Access of insects was prevented by inclosing the plants in a gauze case. The method of feeding consisted in supplying each leaf (on the fed sides of the six plates) with one or two small bits of roast-meat, each weighing about one-fiftieth of a grain, every few days. On July 17th it was evident that the leaves on the “fed” side were of a distinctly brighter green, showing that the increased supply of nitrogen had allowed a more active formation of chlorophyll-grains to take place. From this time forward the "fed" sides of the plates were clearly distinguishable by their thriving appearance and their numerous tall and stout flower-stems. On August 7th the ratio between the number of “starved” and “fed” flower-stalks was 100: 149.1. And on comparing the number of stems actually in flower, it was clear that the starved plants were losing the power of throwing up new flower stems at an earlier date than their rivals. In the middle of August the leaves were counted in three plates, and were found to be one hundred and eighty-seven on the starved and two hundred and fifty-six on