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THE POPULAR SCIENCE MONTHLY. 



trees, which became so painfully apparent 

 during the previous spring, to the action of 

 drought and cold. The year preceding 

 was, in New England, one of the dryest on 

 record, the ground, when winter set in, hold- 

 ing a comparatively small amount of moist- 

 ure. This left the roots of trees deficient 

 in sap. Not being well protected by snow, 

 the ground in winter was frozen to a great 

 depth, and, as the frost left the roots in 

 spring, they remained for some time in con- 

 tact with relatively dry earth, thus causing 

 a shock too great for their vitality to with- 

 stand. During the succeeding summer 

 Prof. Shaler also observed a remarkable 

 scarcity of snakes and toads, which he is 

 likewise inclined to ascribe to the great se- 

 verity of the previous winter. Concerning 

 the effect of such climatic accidents on the 

 character of our forests, he says : 



" Small as the destruction of forest-trees 

 is, it will doubtless add several per cent, to 

 the deciduous trees of New England, and 

 remove an equal amount of conifers. The 

 conifers seem to be relics of an old time, 

 and not competent to wage a successful 

 war with their younger and more elastic 

 competitors, the oaks, beeches, and other 

 deciduous trees. Every gap that is made 

 in our forests of cone-bearing species is 

 filled not with their legitimate successors, 

 but by forms from the other class of trees. 

 Let us suppose that the shock of the last 

 season had been great enough to kill off 

 the whole of our pines, the result would 

 have been a complete change in the charac- 

 ter of our forests ; oaks generally would 

 take the vacant place. This would affect 

 the character of the undergrowth very ma- 

 terially, for the lesser plants of a pine-wood 

 are very different from those which 'flourish 

 beneath oaks. This would have had a very 

 great effect upon insect-life, and more or 

 less directly influenced the number and 

 character of the birds and the mammals. 

 Even the climate would be in some small 

 measure influenced, for a pine-forest retains 

 the snow better than one which loses its 

 leaves in the winter, and thus tends to secure 

 a more equable temperature in the region 

 where it lies. Thus we see that an acciden- 

 tal drought might bring about a change in 

 the assemblage of vital conditions on the 

 surface of the land, as great as those which, 



when recorded in strata, we accept as indi- 

 cating distinct geological formations." 



Dental Art among the Japanese. Dr. W. 



St. George Elliott, formerly of this city, now 

 at Yokohama, Japan, sends to the Dental 

 Cosmos an interesting account of Japan- 

 ese habits in regard to teeth, and of the 

 state of dentistry in that empire. He says 

 that the teeth of the daughters of Japan 

 are objects of envy, and it is remarkable 

 that a nation who place so much value upon 

 their teeth should keep up the custom of 

 blacking them after marriage. As a race 

 the Japanese have not good teeth, and it Is 

 rare to find an old person with any at all. 

 Their tooth-brushes consist of tough wood, 

 pounded at one end to loosen the fibres. 

 They resemble paint-brushes, and owing to 

 their shape it is impossible to get one be- 

 hind the teeth. As might be expected, 

 there is an accumulation of tartar which 

 frequently draws the teeth of old people. 

 The greatest accumulation is behind the 

 lower orals, and these are frequently 

 cemented together by a dense, dark-brown 

 deposit, a quarter of an inch in thickness. 

 Their process of manufacturing false teeth 

 is very crude. The plates are made of 

 wood, and the teeth consist of tacks driven 

 up from the under side. A piece of wax is 

 heated, and pressed into the shape of the 

 roof of the mouth. It is then taken out 

 and hardened by putting it into cold water. 

 Another piece of heated wax is applied to 

 the impression, and, after being pressed into 

 shape, is hardened. A piece of wood is then 

 roughly cut into the desired form, and the 

 model, having been smeared with red paint, is 

 applied to it. Where they touch each other 

 a mark is left by the paint. This is cut 

 away until they touch evenly all over. 

 Shark's-teeth, bits of ivory, or stone, for 

 teeth, are set into the wood and retained in 

 position by being strung on a thread which 

 is secured at each end by a peg driven into 

 the hole where the thread makes its exit 

 from the base. Iron or copper tacks are 

 driven into the ridge to serve for masticat- 

 ing purposes, the unequal wear of the 

 wood and metal keeping up the desired 

 roughness. Their full sets answer admira- 

 bly for the mastication of food, but, as they 

 do not improve the looks, they are worn 



