June 22, 1916] 



NATURE 



347 



nervous impulse, and is an attempt to make more 

 concrete the way in which competing paths may 

 operate. He shows how a synapse mechanism, t.e. 



system of interrelated neurons connected with other 



^tems similarly constructed, by the varying degrees 



: resistance at their junction may ser\e for the selec- 



\e distribution of impulses, and for the linking of 



^ae impression with another in the formation of 



habits. 



The new volume of the Anales of the National 

 Museum of Natural History of Buenos Aires (vol. 

 xxvii., for 1915) contains a very varied series of con- 

 tributions to our knowledge of the natural history of 

 the Argentine Republic. Beginning with some ob- 

 servations on ants, by the director of the museum. 

 Dr. A. Gallardo, it comprises several technical papers 

 on entomology and botany, and deals with many other 

 subjects, ranging from old maps of the River Plate 

 and drawings of the fabulous beast known as the 

 ■ succarath," to a detailed f>etrographical account of 

 some granitic rocks. The exploration of a sepulchral 

 cave on the coast of Chubut leads Dr. F. F. Outes 

 to conclude that during the sixteenth and seventeenth 

 centuries the Patagonians possessed only the bow and 

 arrow as a weapon ; that in the first third of the 

 eighteenth century they began to use the imported 

 horse, and then first emplo\ed the bolas. Photo- 

 o^raphs of well-preser\-ed portions of three arrows, or 

 javelins, provided with a stone tip, are given. 



In the Journal of the South African Ornithologists' 

 Union for December, which has just reached us, Mr. 

 C F. M. Swynnerton gives a long account of his 

 experiments with captive birds in regard to their 

 choice of insect food. For the most part his experi- 

 ments were made with butterflies and moths and 

 their caterpillars, though wasps, beetles, and other 

 insects were also used. The Lepidoptera included 

 both the protectively coloured, edible species and the 

 Nvarningly coloured, nauseous species. He finds that 

 birds will readily eat even the most nauseous forms 

 if they are hungry, but their readiness to accept these, 

 and their ability to retain them when swallowed, 

 decrease rapidly as hunger is satisfied. Thus the 

 warningly coloured species derive benefit from their 

 coloration only when their avian enemies can afford 

 to pass them by. Even those birds with the smallest 

 capacity for eating nauseous insects are able to eat 

 one or two with apparent impunity, and even eager- 

 ness, when their stomachs are empty and the appetite 

 is good. A bird with a rapid digestion is able to go on 

 eating the most nauseous insects indefinitely, with 

 frequent short inter\-als for assimilation, provided that 

 no more tempting insects are within reach to carry the 

 filling of the stomach well beyond the point at which 

 such nauseous morsels are usually refused. Dis- 

 crimination between edible and nauseating forms, the 

 author contends, comes by experience only, and not 

 instinctively. 



In the Ke-w Bulletin, No. 3, ten new exotic fungi 

 are described by Miss E. M. Wakefield. Polyportis 

 shoreae, a serious disease of Sal {Shorea robusta), is 

 illustrated by a photograph showing the large sporo- 

 phore at the base of a tree-trunk in Bengal. Cordy- 

 ceps peltata, a species parasitic on the larvae of a 

 Cryptorhynchus, which infests cultivated Codiaeums in 

 St. Vincent, differs from all other species in the very 

 large spores, which, instead of breaking apart at ever}- 

 septum at maturity, only separate at the middle into 

 two narrowly wedge-shaped halves. The description 

 of the fungus is illustrated by text figures. 



In the Journal of Botany for April Dr. \V. Botting 

 Hemsley contributes a paper on the flora of the Sey- 

 chelles and Aldabra, giving descriptions of new flower- 



NO. 2434, VOL. 97] 



ing plants collected mainly during Prof. J. Stanley 

 Gardiner's Percy Sladen Trust Expedition in 1905. 

 Fifteen new species are described in the present con- 

 triburton, which includes the Rubiaceae and the de- 

 scription of a new Impatiens drawn up in 1910 by 

 the late Sir J. D. Hooker. Some emendations in 

 synonymy are also made. In a short introduction 

 Dr. Hemsley gives an account of the botanical collec- 

 tions made in the Seychelles since 190 1, when the 

 flora of the islands was being critically studied by 

 the author. 



A SUBJECT of considerable importance to officers is 

 most clearly and simply treated by Mr. E. A. Reeves 

 in a paper on " Night Marching by Stars " in the 

 Geographical Journal for June (vol. xlvii.. No 6.). A 

 good deal has recently been published on the subject, 

 but no one perhaps has to such an extent the happy 

 way of Mr. Reeves of putting technicalities in simple 

 language. This paper, based on a lecture delivered at 

 the Royal Geographical Socier\-, deals both with the 

 methods of finding the bearings of stars at any time 

 and the more practical issue of using these bearings 

 in marching. 



An important paper in Swedish by V. Tanner, 

 occupying more than 800 pages, describes the develop- 

 ment and retreat of the continental ice in Finnish and 

 Scandinavian Lapland {BiilL de la Comm. giol. de 

 Finlande, No. 38, 1915). A good resume in French is 

 given. Numerous eskers have been examined, and 

 the author points out that several of these have 

 suffered since their formation from fluvioglacial 

 erosion and deposition. He takes the view, now 

 common, that the eskers arose in tunnels in or under 

 the ice-sheet, the eskers with "centra," described by 

 De Geer, from the Stockholm district being special 

 cases of formation where the ice-front abutted upon 

 a lake or sea. The author wishes to reserve judgment 

 as to whether centra in the eskers of Lapland have 

 been produced in the same manner. Good illustra- 

 tions are given of the gorges cut by glacial waters 

 during the epoch of ice-recession. The work repre- 

 sents field-obser\'ations, extending over several years, 

 in a country sparsely inhabited, difficult to traverse, 

 and of singular monotony from the scenic point of 

 view. The glacial map forming plate i., which un- 

 fortunately has no place-names, sufficiently attests the 

 author's industry, covering an area of "350,000 sq. 

 kilometres, or some 135,000 sq. miles, between lati- 

 tude 66° 30' N. and the desolate tundras that bound 

 the Arctic seas. 



We have received Revista de la Academia de Cieti- 

 cias, etc. (vol. i.. No. i. May, 1916; Zaragoza), and 

 " La Ciencia, La Universidad, y La Academia," the 

 latter being an inaugural address by Dr. Zoel G. de 

 Galdeano. Their principal interest is that they show 

 that Spain is beginning to appreciate the value' of the 

 exact sciences. 



As supplementing the information given in the note 

 on the " Mineral Resources of Great Britain," vol. v., 

 which appeared in Nature of June 15 (p. 327), refer- 

 ence may be made to the account of the occurrences of 

 molybdenum ores throughout the world which ap- 

 peared in the Bulletin of the Imperial Institute, No. 2 

 of 1908. The information then published was brought 

 up to date by a special circular, issued by the Imperial 

 Institute in 1915, dealing with occurrences of molyb- 

 denite in the British Empire, which are either com- 

 mercially productive or afford promise of becoming so. 

 The collection and publication of information respect- 

 ing the occurrence of economic minerals in the Colo- 

 nies and India has for some years been a prominent 

 part of the operations of the Imperial Institute. 



