2/4 



NATURE 



[April 27, 191 1 



established itself as far north as Bordeaux, it is for- 

 tunate that no species has yff ^••'•■' 'hie to do so in 

 tho British Isles. 



Prof. Eschcrich first dcvolid his attention to the 

 termites during a tour in northern Abyssinia (Erythrea) 

 four years ago, and, wishing to continue his studies on 

 the same subject, selected Ceylon as most suitable for 

 his purpose. Incidentally he estimates the number 

 of species of termites already described as about 500. 

 whereas about 5,000 species of ants are known. It is 

 probable, however, that the difference is not solely due 

 to termites having been less studied than ants, but to 

 the number of species of the former being really much 

 less numerous. The number of termites now known 

 from Ceylon is thirty-five, of which four are possibly 

 forms of others, leaving thirty-one undoubted species, 

 nearly all collected by Prof. Escherich himself. The 

 species of ants collected by Prof. Escherich in Ceylon 

 number about seventy. He must have worked hard 

 during his short stay in the island (from January 22 

 to the end of the first week in April), of which he 

 gives an interesting account. 



The first chapter of the main work is de- 

 voted to the nests of the mound-making ter- 

 mites, which vary much in form and size, 

 and usually contain large fungus-beds. The larger 

 termite-hills in Ceylon rise to a height of from 

 2 to 2^ metres, and the subterranean part is said by 

 the natives to extend to a depth of ^ to i metre. The 

 inhabitants of the nests are also described, and com- 

 pared with the African Termes hellicosus. The latter 

 species, however, is far more formidable, for the 

 mandibles of the soldiers draw blood at every snap, 

 while those of the Ceylon species can hardly pierce 

 the skin of the hands, though they cling on firmly, 

 and discharge an irritating liquid. Prof. Escherich 

 disputes the usual notion that light is intolerable to 

 termites ; but it seems to us probable that this sensi- 

 tiveness varies in different species. The huge size 

 to which the abdomen of tho queen termite attains is 

 well known, but still more remarkable in the opposite 

 direction is the figfure of a soldier on p. 54, the head 

 of which is nearly as large as the body, and the head 

 and mandibles together much longer. 



Several species of termites often inhabit one nest, 

 and different species of ants are often associated with 

 them in the same nests, as well as many other in- 

 sects, &c. One peculiarity of the termite hills is the 

 so-called " chimneys," open above, and running down 

 into the nest, and efficiently providing for ventilation. 



The second chapter of the book deals with the 

 genus Eutermes, the species of which make their nests 

 in wood, and are exceedingly destructive, while others 

 construct long galleries, throup-h which they march 

 from one place to another. A third chapter is devoted 

 to miscellaneous observations on queens, soldiers, 

 behaviour towards light, &c., and a fourth to the 

 economic importance of termites. Prof. Escherich con- 

 siders that they are much less destructive in Ceylon 

 than in Attica, and he discusses the best means of 

 preventing their ravages, or of destroying them. 

 The book concludes with a series of valuable ap- 



NO. 2165, VOL. 86] 



pendices by various authors, including d« - of 



a considerable number of new species < by 



Prof. Eschcrich, comprising termites, ants, and 

 various Colcoptera, Orthoptera, Thysanura, Myria- 

 poda, and Nemotoda, inhabiting the nests of termites 

 in Ceylon. 



W 



ORIENTATION IN ORGANIC CHEMISTRY. 

 Ober die Bestimmung des chemischen Ortes bei den 



aromatischen Substanzen. By W. Koerner. Pp.. 



132. (Leipzig : W. Engelmann, 1910.) Price 2.^^om 



marks. ■ 



ILHELM KOERNER had the good fortune 

 to become a student of Kekul^, in 1865, at a 

 time when the latter was developing his benzene 

 theory. After a year spent in Otling's laboratory, 

 Koerner returned to Ghent as private assistant to 

 Kekul^, and remained for a year in that capacity. 

 He rapidly imbibed the views of his teacher, 

 and, realising something of their far-reaching 

 consequences, set before himself the task of 

 experimentally demonstrating the truth of Kekuld's 

 theory, a task which he never afterwards relinquished. 

 The object of his first paper, published in 1866 in the 

 Comptes rendus, was to link together the three series 

 of di-derivatives of benzene. Thus, by preparing the 

 three iodophenols and converting them by fusion with 

 potash into the corresponding hydroxybenzenes, he was 

 able to connect quinol with iodoaniline, iodophenc^ 

 with catechol, and nitraniline with resorcinol, incor- 

 rectly regarded as the ortho, meta, and para series 

 respectively. At the same time he criticised the 

 speculative methods adopted by Baeyer, Graebe, and 

 others as a basis for orientation. 



In his second paper, published in 1867, he fore- 

 shadows his future method by pointing out that the 

 trihydroxybenzene derived from the three dihydroxy- 

 compounds must have the hydroxyls in the i, 2, 4 

 position. His third paper contains a clear exposition 

 of Kekul^'s views on the constitution of the aromatic 

 series with which we are so familiar. It is dated 

 1869 from the laboratory of Cannizzaro at Palermo, 

 whither he had gone in 1867 to re-establish his health. 

 When, later, he became lecturer on organic chemistry 

 at the new technical college in Milan, he continued 

 actively engaged in experimental work connected with 

 his method of orientation, which he embodied in his 

 fourth paper, published in 1874 in the " Gazzetta 

 chimica italiana." It is in this last paper that Koernert 

 collected the enormous mass of material which hadi 

 been steadily accumulating since 1867. i 



The work, establishing for the first time by direct- 

 experimental evidence the true orientation of the 

 simpler benzene derivatives, has taken its place as 

 one of the classics of chemical literature, and chemists 

 will welcome this last addition to Ostwald's Klassiker. 

 The papers have been translated from French and 

 Italian by Messrs. Bruni and Vanzetti, who have 

 added a few explanatory notes. They have over- 

 looked a curious transposition of the ninth line from 

 the bottom of p. 4, which should be read as the 

 bottom line. J- B. C. 



