February 25, 191 5] 



NATURE 



7^7 



west side of the originating fault, and when the 

 barometric gradient is directed to the south-east. On 

 the other hand, he can discern no relations between 

 earthquake-frequency and changes in barometric pres- 

 sure or the tides of the neighbouring coast or sun- 

 spot maxima or lunar periodicities. 



Dr. E. Warren gives, in the Annals of the Natal 

 Museum for September, 19 14 (vol. iii., pt. 1), a full and 

 well-illustrated description of a remarkable plumu- 

 larian hydroid zoophyte discovered on living ojsters in 

 191 1 on the coast of Pondoland, of which a preliminarj' 

 notice has already appeared. Although nearly allied 

 to those species of Plumularia with hydrothecae arising 

 from the main stem, it differs by the presence of 

 pinnules on some of the pinnae, thereby approaching 

 Schizotricha, in which nearly all the pinnae are thus 

 furnished. It is therefore provisionally included in 

 that genus, as 5. simplex. Its main claim to interest 

 Is, however, connected with its reproduction, which is 

 of a unique type. Instead of the egg being furnished 

 with a yolk-supply sufficient to maintain the young 

 until capable of foraging for itself, as in the great 

 majority of invertebrates, " the egg remains quite 

 small and is never provided with a perceptible quantity 

 of yolk, but segments, and development takes place, in 

 a kind of maternal placental tissue which supplies 

 the embryo with food during the whole development." 

 In another article in the same issue Mr. H. C. Burnup 

 reviews the minute pyramidal striated S. African land- 

 snails of the genus Ennea, with descriptions of new 

 species and races. 



The recently received number of the Philippine 

 Journal of Science (vol. ix., sec. c, No. 4, August, 

 19 14) contains two papers by Mr. E. D. Merrill, in 

 which no fewer than ninety-three new* species of 

 Philippine plants are described. Forty-three were 

 collected by Wenzel in the island of Leyte, whose 

 collections have already added very largely to a 

 more complete knowledge of the rich flora of the 

 archipelago. The other new species come from 

 various islands, and are included in Mr. Merrill's 

 tenth and concluding instalment of new or note- 

 worthy Philippine plants. 



Steps are being taken to secure the trade in senna 

 In British hands. The plant from which the finest 

 quality of senna is obtained grows in the Sudan, 

 where the leaves and pods are collected and dried by 

 natives, and sold to collecting agents for export. At 

 one time this trade was entirely British, and the pro- 

 duce was sold through London, but afterwards it 

 passed into German hands. The Imperial Institute 

 has been in communication with the chief British 

 importers and with the Egyptian Government, and the 

 export of senna from Egypt has now been prohibited 

 except to the United Kingdom and France. British 

 firms are making arrangements direct with the native 

 growers, which should not only restore the trade to 

 this countrv', but lower the price and secure the purity 

 of the supply. 



Mr. W. G, Reed, of the Department of Geography 

 of the University of California, presented a paper, 

 "Climatic Provinces of the Western United States," 

 NO. 2365, VOL. 94] 



to the Cordilleran Section of the Geological Society 

 of America, and this paper has been printed in the 

 Bulletin of the American Geographical Society (vol. 

 xlvii.. No. i). After discussing various classifications, 

 such as those of Supan and Herbertson, Mr. Reed 

 advances a new classification based uix>n considera- 

 tions of rainfall, temperature, and relief. The area 

 from the coast to the Rockies is divided into four 

 main regions, a northern and southern coast strip 

 divided at 40° N., and a northern and southern "rain- 

 shadow " strip divided about 43° N. The coast strips 

 are subdivided mainly for topographical reasons into 

 smaller divisions. The main divisions are, on the 

 whole, just, since the whole rain-shadow area is char- 

 acterised by a relative raininess in the month of 

 May, which is lacking along the coast strip, but it 

 seems probable that Mr. Reed has not made sufficient 

 allowance for two facts regarding the coast strip. In 

 Washington the month of maximum raininess is 

 November, and the further south one goes the later 

 in the season does this maximum occur, and at the 

 same time the relative raininess shows considerable 

 increase. Probably these facts would have com- 

 manded attention had Mr. Reed made rainfall graphs 

 in a generalised form for his subdivisions instead of 

 taking single places as types. 



In the Philosophical Magazine for January- Mr. 

 A. E. Young obtains formulae for the effect of stiffness 

 and stretching on the form of a suspended wire or 

 tape. The importance of these investigations largely 

 depends on their application to the steel tapes and 

 other substitutes for the old chain in modern survey- 

 ing. 



In a paper communicated to the Proceedings of the 

 Cambridge Philosophical Society (xviii., 2), Dr. Nor- 

 bert Wiener proves in a short note that the shortest 

 curve dividing a given area in a given ratio consists 

 of a circular arc or a number of such arcs, each ter- 

 minated on the boundary of the area. The paper was 

 originally intended to be a joint article by the author 

 and Dr. SzAsz, and to contain a proof that the shortest 

 curve dividing any scalene triangle in a given ratio is 

 a circular arc with the most acute apex as centre. 

 Owing to the war this has not been possible, but the 

 results are so self-evident to an average English 

 mathematician that no advantage would have been 

 gained by a further discussion in print. The simplest 

 plan is to replace the author's words, "dividing an 

 area in a given ratio" by "cutting off a segment of 

 given area from a given closed figure." The proof 

 that the portion of the curve joining any two points 

 on it is an arc of a circle is found in most text-books, 

 and the reader should have no difficulty now in seeing, 

 further, that the arc in question must meet the 

 boundar)' at right angles (unless it {>asses through 

 a re-entrant angle), whence the property- which Dr. 

 Szasz intended to prove follows immediately. 



The December number of Terrestrial Magnetism 

 and Atmospheric Electricity contains the results of the 

 determinations of the deviation of the compass made 

 on the magnetic survey ship Carnegie during her 

 voyages from Brazil to St. Helena in 1913, and from 



