BIOLOGY. 275 



carbonic acid and the evolution of oxygen through the chlorophyll, 

 under the influence of light, explain some of the movements of 

 these minute colored organisms. 



TALL TREES IN AUSTRALIA. 



From Dr. F. Miiller's pamphlet upon "Australian vegetation, 1 ' 

 it appears that the great trees of California are surpassed in height 

 by the Eucalyptus of Victoria Colony, Australia. From actual 

 measurements these trees attain a height of 480 feet, higher 

 than the spire of Strasburg cathedral, and as high as the great 

 pyramid of Cheops. They are not, however, so thick as the 

 California trees, a tree 400 feet high, having a circumference of 

 only 40 to 50 feet, though they have been found with a circum- 

 ference of 81 feet at a distance of 4 feet from the ground. The 

 enormous height of vast masses of timber trees in the rich diluvial 

 deposits and sheltered depressions in the Victoria ranges is attrib- 

 utable to the richness of soil, humidity of climate, and moderate 

 temperature of the region. The absence of living gigantic forms 

 of animal life amid this colossal vegetation is very striking. 

 These trees are also remarkable for their rapid growth, even on 

 dry and exposed spots, and for their fitness to resist drought. 



He says that "in Australian vegetation we probably possess the 

 means of obliterating the rainless zones of the globe, to spread at 

 last woods over our deserts, and thereby to mitigate the distressing 

 drought, and to annihilate, perhaps, even that occasionally ex- 

 cessive dry heat evolved by the sun's rays from the naked ground 

 throughout extensive regions of the interior. . . . How much last- 

 ing good could not be effected, then, by mere scattering of seed 

 of our drought-resisting acacias and eucalypts and casuarinas, at 

 the termination .of the hot season, along any water-course, or even 

 along the crevices of rocks, or over bare sands or hard clays, after 

 refreshing showers ? Even the rugged escarpments of the deso- 

 late regions of Tunis, Algiers, and Morocco might become 

 wooded ; even the Sahara itself might have its oases vastly aug- 

 mented ; fertility might be secured again to the Holy Land, and 

 rain to the Asiatic plateau, or the desert of Atacama, or timber 

 and fuel be furnished to Natal and La Plata." 



SKELETON LEAVES. 



The following method has been communicated to the Botanical 

 Society of Edinburgh: "A solution of caustic soda is made by 

 dissolving 3 oz. of washing soda in 2 pints of boiling water, and 

 adding 1 oz. of quicklime, previously slacked ; boil for 10 min- 

 utes, decant the clear solution, and bring it to the boil. During 

 ebullition add. the leaves; boil briskly for some time, say an 

 hour, occasionally adding hot water to supply the place of that 

 lost by evaporation. Take out a leaf and put it into a vessel of 

 water ; rub it between the fingers under the water. If the epider- 

 mis and parenchyma separate easily, the rest of the leaves may 

 be removed from the solution, and treated in the same way ; but 



