August 21, 19 13] 



NATURE 



647 



who wishes to see the scientific methods in vogue on 

 the Continent brought to bear on the waste lands of 

 these islands, should be without a copy of this illu- 

 minating address. It concludes with the statement 

 that " the Belgian Government obtains on the capital 

 it has invested in forestry a return varying from 4-9 

 to 5-5 per cent." In his retiring address as president 

 (Proc, p. 10) he adds: — "Scotch forestry is in the 

 toils of the serpent of red tape. In spite of our 

 efforts to keep it free and independent, forestry is now 

 entangled with a number of different departments, 

 some of which in the nature of things can know 

 very little, and perhaps do not care very much, about 

 the subject." 



Mr. B. Ribbontrop, who, for many years, was head 

 of the Indian Forest Department, gives a summary 

 of Dr. R. Albert's researches on the peat soils of 

 north-west Germany. 



The true character of the seedlings of Japanese 

 larch raised from Scotch seed was discussed at last 

 summer's meeting of the English Arboricultural 

 Society. On one hand, the time (one generation) 

 seemed too short for the environment to have altered 

 so considerably the character of the seedlings. On 

 the other hand, the alteration seemed to be too 

 uniform for hybrids between Larix enropaea and 

 Larix leptolepis. Mr. A. Murray, writing from 

 Murthly, where these seedlings have been closely 

 watched from the first, now gives the opinion that 

 they are not hybrids. It may be noted that a similar 

 alteration has been remarked in the case of an Aus- 

 tralian Eucalypt that had been one generation in 

 southern France. 



For extracting tree-stumps with gelignite, Dr. 

 Lauder gives the following working formula : — For 



square of girth in feet , . , .,,. 



pine stumps, — — =cost in shillings 



of explosive ; and for broad-leaved trees — oak, ash, 

 elm, &c- — about double the cost of pines and firs. 



THE MANUFACTURE OF ARTIFICIAL 

 TEETH. 

 T N the Bulletin de la Societi d'Encoitragcment for 

 *■ April last is an interesting and well-illustrated 

 article on " La fabrication des Dents Artificielles 

 Minerales," by M. Maurice Picard, of the firm of 

 MM. Henri Picard and Co., read at the opening 

 ceremony of the first factory established in France, 

 at Versailles, in the presence of M. Lechevalier, the 

 representative of the Minister of Commerce and In- 

 dustry. 



The making of artificial teeth has for more than 

 fifty years been a small but important industry in 

 England and America, where millions of teeth of 

 many shades and shapes are annually manufactured. 



This industry owes its origin and early develop- 

 ment to illustrious Frenchmen. Pierre Fauchard, in 

 his work, " Le Chirurgien-dentiste," 172S, first sug- 

 gested the use of enamel. Duchateau in 1744 sub- 

 stituted porcelain for ivory, with the aid of the porce- 

 lain manufacturer M. Gerrard, of Paris. Later 

 Duchateau, with Dubois de Chaumant, a dentist in 

 Paris, who suggested the addition of pipe-clay, made 

 great improvements in manufacture. The latter car- 

 ried the invention to England, and obtained a patent 

 in 1791 for fourteen years. In 1808 Fonzi, a dentist 

 in Paris, fixed platinum pins into the body of the 

 tooth, as a means of attaching the tooth to the arti- 

 ficial plate which holds it in position. M. Plantou 

 manufactured artificial teeth in America in 1817. 



Felspar and silica ground to an impalpable powder, 

 to which is added a certain amount of kaolin, form 

 the basis of all porcelain teeth. These are made into 



NO. 2286, VOL. 91] 



a thick paste, and tinted in a variety of colours with 

 oxide of titanium. The paste is pressed into moulds 

 in which are inserted platinum pins. These teeth are 

 then fused in a furnace at a very high temperature. 

 The factory in Versailles already manufactures 225,000 

 teeth each month. 



Incidentally, one may inquire why such an inven- 

 tion should not have found, sooner, an industrial 

 home in the land of its origin? The answer may be 

 suggested, not in lack of enterprise, but in the facts 

 that French people do not readily part with their 

 natural teeth, and they have an innate objection to 

 artificial teeth on plates. 



We have no doubt that the refined foods of an 

 advancing civilisation are leading to an increased 

 destruction of teeth by dental caries. We have no 

 evidence to prove that" our neighbours' teeth, how- 

 ever, are better than our own, but they submit more 

 readilv to the conservative treatment which dentists 

 are trained to give in the preservation of teeth, rather 

 than permit the ravages of the arracheur de dents. 



R. D. Pedley. 



THE MUTATIONS OF OENOTHERA. 



I^HE last decade has witnessed many remarkable 

 advances in our knowledge of heredity and 

 variation. The beginning of the present century may 

 be said to mark the turning-point between the 

 observational method of Darwin and the more in- 

 tensively experimental method now pursued in the 

 study of evolution. This change from observation to 

 experiment in evolutionary study was participated in 

 by many investigators. Among those whose work 

 will ever occupy a prominent place in the renaissance 

 of activity .in scientific plant- and animal-breeding 

 may be mentioned de Vries, whose theory of muta- 

 tion, or the sudden origin of new species, has been 

 a fruitful subject of investigation and discussion. 



The views of de Vries, published in 1901, were 

 based to a considerable extent upon his prolonged 

 investigations with the evening primrose, CEnothera 

 Lamarckiana. These now classic experiments showed 

 that when this species is cultivated in large numbers, 

 individuals appear sporadically but repeatedly year 

 after year which differ from the type in nearly all 

 their characters. These new types, or mutants, in 

 many cases breed true, giving rise to new races, and 

 the main facts of de Vries's observations have since 

 been repeatedly confirmed. 



It is safe to say that these remarkable and at that 

 time unique observations have subsequently led to a 

 more thorough and complete study of the evening 

 primroses than has been accomplished in any other 

 group of plants, not even excepting the garden pea 

 of Mendelian fame. Numerous investigators have 

 attacked the problem thus presented from many points 

 of view, and much light has been thrown upon the 

 general subject of mutations. This is particularly 

 true of the cytological investigations, which have 

 really furnished the key to the explanation of the 

 mutation phenomena. 



Since a fortunate discovery in 1906 indicated that 

 various mutants differed in the constitution of their 

 nuclei, the origin of these differences has been an 

 absorbing subject of investigation. Two years later 

 it was possible to show that a basis for changes in 

 the nuclear constitution of different mutants exists in 

 the germ cells, and that the process of mutation is 

 probably in part a result of irregularities in chromo- 

 some distribution during meiosis or germ-cell forma- 

 tion. The chromosomes are the constituent parts of the 

 nucleus, and their number is constant for each species, 

 so this furnished the desired proof that, in some 



