September io, 1914] 



NATURE 



39 



observed with the theoretical figure is remarkably close ; 

 in fact Mr. Adams states that '" the mirror may accord- 

 ingly be regarded as essentially perfect to within the 

 limit defined in this way." A similar set of tests 

 made by Mr. Knox-Shaw on the old thirty-inch Com- 

 mon mirror in situ in the telescope. He found that 

 the mirror was uncorrected by about twice as much as 

 was the Ritchey mirror at the time of the first series 

 of tests mentioned above. From tests of the astig- 

 matism he concludes that the position of the telescope 

 has an appreciable effect on the figure of the mirror 

 as has been suspected to be the case. 



PLANT-LIFE AT THE SNOW-LINE.^ 



MR. JOSIAS BRAUN'S exhaustive account of the 

 vegetation at the snow-line in the south-eastern 

 (Rhaetian-Lepontine) Alps forms a valuable contribu- 

 tion to our knowledge of the plant-ecology of the 

 Swiss Alps. The area includes, roughly speaking, 

 the country from the St. Gothard to the Engadine. The 

 text consists of two parts. The first is a consideration 

 of the vegetation in relation to external conditions, 

 with a detailed description of the plant-associations. 

 The zone under consideration is defined as thai in 

 which the summer heat just suffices to melt the annual 

 heavy snow-fall on level areas ; its altitude ranges 

 from 2960 metres on the Bernina chain to 2650 metres 

 in the St. Gothard group. It lies above the region 

 of close turf, and forms a part of the open rock re- 

 gion. Within it the author distinguishes three 

 secondary zones: (i) the " Pionierrasengurtel," the 

 isolated outposts, so to say, of the turf-flora, forming 

 patches in wind-sheltered places or on sunny spots ; 

 (2) the "Dicotyledonous zone," characterised mainly 

 by cushion-forming Dicotyledonous plants ; and (3) 

 the " Thallophyte-zone " of rock-inhabiting lichens. 

 The principal natural formations in the first zone are 

 the Curvuletum, of which Car ex curvula is a charac- 

 teristic component, and the Elynetum, in which Elyna 

 myosuroides predominates. Here, too, are found the 

 last traces of the influence of man and his domesti- 

 cated animals, indicated by luxuriance of Poa alpina. 

 The last chapter of the first part deals with the fauna 

 of the area, which comprises ninety-one species, 

 mainly insects and spiders. 



The second part comprises a systematic account of 

 the flora. This includes two ferns, Cystopteris fragilis 

 and Asplenium viride, Botrychium lutiaria, Lycopo- 

 diutn selago, Juniperus communis var. montana, and 

 219 angiospermous flowering plants. The latter repre- 

 sent twenty-nine families, those most in evidence 

 being, in order of numerical preponderance., Com- 

 positae, Gramineas, Caryophyllaceas, Saxifragaceae, 

 Cruciferae, Rosaceae, Leguminosae, Gentianaceae, 

 and Primulaceae, which together contain two- 

 thirds of the whole flora. The proportion of 

 Monocotyledons to Dicotyledons is slightly less than 

 at lower levels, namely, i : 43 as compared with 

 I : 36. There are nine woody plants : Juniper, three 

 Willows, Einpetrum. nigrum,, Loiseleuria (Azalea) 

 procumbens, and three species of Vaccinium. The 

 best represented genera are Saxifraga, sixteen species ; 

 Gentiana, ten species ; Carex, nine species ; Festuca, 

 Draba, and Cerastium, each with six species ; and 

 Alchemilla and Primula each with five. A compari- 

 son with the Arctic flora of the west coast of Green- 

 land, between N. lat. 69° and 71°, which contains 

 approximately the same number of flowering plants, 

 shows considerable agreement between the two. 

 There is, however, a much greater proportion of marsh 

 plants in the Arctic flora, while in the Alpine the 



1 Noiiveaux Mimoires de la Soci«ttf Helvetique des Sciences NatureHes, 

 vol. xviii. Pp. vii + 347 + map + 4 plates. 



families Compositae, Primulaceae, Gentianaceae, and 

 Leguminosae are more richly represented. 



The author groups the snow-flora of this district of 

 the Alps under five main headings: (i) an endemic- 

 Alpine element, peculiar to the Alps, comprising 

 twenty-nine species (13 per cent.); (2) a European- 

 -Alpine element with ninety-five species (42-4 per cent.) ; 

 (3) a Euraslatic element with fourteen species (6-2 per 

 cent.), which occur also in Central Asia, but do not 

 reach the polar circle; (4) an Arctic-.-Mpine element 

 with seventy one species (31-7 per cent.); (5) a ubiqui- 

 tous element, fifteen species (67 per cent.), of more 

 widely distributed plants in lower levels. 



RECENT WORK ON ENTOMOLOGY. 



npHE American representatives of the minute homo- 

 -*■ pterous insects commonly known as jumping 

 plant-lice (Psylliidas) form the subject of an elaborate 

 memoir by Mr. D. L. Crawford, published as Bulletin 

 No. 85 (168 pp.) of the U.S. National Museum. These 

 widely-spread insects frequent trees and shrubs, where, 

 from their active habits, they are difficult to capture 

 without the aid of a net. When disturbed, they throw 

 themselves into the air by means of their powerful 

 hind-legs, and when once launched, are able to propel 

 themselves some considerable distance by rapidly 

 vibrating the wings, although they are not endowed 

 with the power of prolonged flight. 



Mr. Crawford found the current classification of the 

 group — largely based on wing-venation — to be alto- 

 gether untrustworthy, closely related species being in 

 many instances placed in different genera. A more 

 satisfactory basis for classification is afforded by the 

 structure of the head ; and from this and other features 

 the author proposes a new taxonomic scheme, with the 

 description of many new species. 



Cicalas and other Homoptera collected during the 

 second expedition of the Duke Adolf Friedrich of 

 Mecklenburg are described by Dr. L. Melichar in 

 Lief. 5 of Band i. of Ergebnisse der Zweiten Deutschen 

 Zentral-Afrika-Expedition, 1910-11. The collection in- 

 cluded 184 specimens, referable to 65 species, of which 

 18 appeared to be new, some of these likewise repre- 

 senting three new genera types. 



In the first article of Lief. 4 of the publication just 

 quoted, Prof. Y. Sjostedt records the white ants 

 observed and obtained during the expedition. Special 

 interest attaches to photographs of the interior of a 

 nest of Termites natalensis, showing, not only a 

 " fungus-garden," but also the royal cells, of which 

 one contains the monstrous, overgrown queen, and a 

 second, in close proximity, the diminutive king. 



In connection with the above may be noticed the 

 description, by Mr. S. Hozawa, in Annot. Zool. Japon, 

 vol. viii., parts 3 and 4, of a new species of termite- 

 eating beetle from Formosa. It belongs to the tene- 

 brionid genus, Zielas, previously known only by a 

 single species from Annam, of which the habits have 

 not been observed, although, from its affinity to 

 termitophilous genera, it has been assumed to feed 

 on white ants. The elongated eyes, degenerate hind- 

 wings, and sluggish movements of the Formosan 

 species are doubtless connected with its mode of life., 



Three issues of the Journal of the College of Agri- 

 culture, Tohoku Imperial University, Sapporo, 

 Japan, are to hand, two of which (vol. v., parts 6 

 and 7) are devoted to various groups of Japanese 

 [ Insects, with descriptions of a number of new species 

 and genera, while the third (vol. vl., part 1) contains 

 further obsen'atlons on reduplication in silkworms. 



Pine timber in a district in Montana, between the 

 , Swan and Clearwater rivers, is seriously menaced by 



NO. 2341, VOL. 94] 



