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NATURE 



[January 21, 19 15 



profitably added a mixture of ammonium phosphate 

 and cane-sugar. The minimum visibile (apart from 

 the ultra-microscope) is discussed by Mr. A. A. C. 

 Eliot Merlin, who finds that the diameter of a particle 

 just visible under a i/i2th apochromat with a working 

 aperture of 1-4 is i /377,358th of an inch. The 

 diameter of the flagellum of Bacterium termo was 

 estimated by Dallinger at 1/ 204,700th of an inch, but 

 Merlin finds it to be about double that, namely, 

 1/112,200. C. F. Rousselet has a note on the sexual 

 stages of two African species of Volvox, Volvox 

 africanus and V. rousseleti. the vegetative colonies 

 of which were previously described by Prof. G. S. 

 West. Mr. E. M. Nelson discusses various forms of 

 binocular microscope, a much-needed low-power con- 

 denser, and a new object glass produced by Zeiss in 

 which a near approach has been made towards apo- 

 chromatism without the use of fluorspar. Just as 

 oil immersions have eclipsed water immersions, so 

 will this new lens, according to Mr. Nelson, super- 

 sede the wide-angled dry lenses, which should all be 

 scrapped. 



The Kew Bulletin, No. 10, 1914, contains a paper 

 on Hedychium coronarium and allied species, which 

 is of value in connection with the interest aroused 

 in these plants as a source of material for paper- 

 making. The eight allied species are chiefly distin- 

 guished by the floral characters, of which illustrations 

 are given. It seems probable that all these Hedy- 

 chiums would be useful for paper-making. It will be 

 remembered that the paper made from this plant is 

 self-sized, and can be written upon with ink directly 

 it leaves the machine without further treatment. 



The native plants of the Azores are discussed by 

 Dr. H. B. Guppy in Kew Bulletin, No. 9, 1914. The 

 vegetation of the mountain of Pico, 7613 ft., was 

 particularly studied, with its European flora on the 

 higher levels — ling, St. Dabeoc's heath, thyme, etc. — 

 and the characteristic Azorean plants below 5000 ft., 

 such as Erica azorica, Juniperus oxycedrus, and the 

 Azorean holly. Ilex perado. The Faya tree, Myrica 

 faya, is a dominant tree in the lower woods, but the 

 forest trees generally are small, owing to the depreda- 

 tions of the wood-cutters- The indigenous plants are 

 few, the flora is largely European in character, with 

 a few affinities with Africa and the Canaries, Myrsine 

 Africana affording the most remarkable connection 

 with the continent. It seems probable that the flora 

 of the Azores is relatively recent and can be 

 accounted for by existing agencies of dispersal in 

 contrast to the Canaries and Madeira, the flora of 

 which is ancient, dating back probably in part to 

 Miocene times. 



The occurrence of pitchblende in the Quartz Hill 

 district, Gilpin Co., Colorado, is described by Mr. 

 E. S. Bastin in Professional Paper, 90 A, United 

 States Geological Survey (19 14). The ore is found 

 in veins with pyrite and copper pyrites, and is con- 

 nected by the author with Cainozoic intrusions of 

 monzonite (diorite with orthoclase). 



Since the reference made in Nature of November 

 26, 1914 (vol. xciv., p. 348) to the Upper Jurassic 

 NO. 2360, VOL. 94] 



fauna of the Spiti Shales of the Himalayas, the study 

 of the mollusca has been continued by Miss Paula 

 Steiger in Vienna {Palaeontologia Indica, series xv., 

 vol. iv., fasc. No. 5). The author wisely remarks that 

 the comparison of the brachiopods with Mediterranean 

 forms is due to our far too scanty knowledge of mem- 

 bers of the group from other parts of the world. 

 Here we have a hint to palaeontologists and collectors. 



The 792 pages of the Annual Report of the Geo- 

 logical Survey of Iowa for 19 13, which has just been 

 issued, are almost entirely occupied by an elaborately 

 illustrated account of the materials for roads and 

 concrete throughout the State. This systematic report 

 provides much information about the nature of the 

 glacial and interglacial beds. In places, the imported 

 boulders of gneiss and granite in the thin lowan drift 

 are as valuable as those in the North German plain, 

 and are similarly collected for use on the macadamised 

 roads. 



In the December number of the Agricultural 

 Students' Gazette, Prof. G. S. Boulger discusses some 

 problems of ecology as illustrated by Gloucestershire 

 flowering plants. He divides the factors of ecology 

 into three main groups, (a) the inherent characters of 

 the plants, (b) the environment, and (c) the relations 

 of (a) and (b). Many species of plants, commonly 

 regarded as characteristic of a particular feature in 

 their normal environment, are found flourishing under 

 conditions where this very feature is notably weak 

 or even absent. Thus, the calcicole or lime-loving 

 Pasque-flower {Anetnone Pulsatilla, Linn6) will grow 

 well in a rich garden soil poor in lime ; the Bee Orchis 

 {Ophrys apifera, Hudson), most commonly found in 

 England on limestone, is also luxuriant on the Upper 

 Lias, near Leckhampton. Again, the Fritillary 

 {Fritillaria meleagris, Linn^) occurs habitually in 

 meadows liable to inundation, but has been found in 

 a wood near Fairford fully twenty feet above the 

 water level. Another species of riverside plant, the 

 Meadow Crane's-bill {Geranium pratense, Linn^), 

 abundant by Severn and Avon at Tewkesbury, is not 

 uncommon in seemingly dry hedgerows on the Cottes- 

 wolds. Little is known of the precise conditions that 

 determine the topographical distribution of common 

 species, and a plea is put forward for the investigation 

 of these and other interesting problems suggested in 

 the paper. 



We have been favoured with a copy of an interesting 

 address by Dr. F. A. Carpenter (local forecaster) 

 entitled " Flood Studies at Los Angeles," reprinted 

 from the U.S. Monthly Weather Review of June last. 

 The object of the paper (which is accompanied by 

 tables and diagrams) is to explain, generally, some 

 of the causes and pertinent features of such rain 

 storms, and to investigate more particularly that of 

 February 18-21, 1914. The rainfall of South Cali- 

 fornia is subject to great variations ; the average 

 annual fall at Los Angeles is 155 in., the extremes 

 being 56 in. (1898-9), and 2^-2 in. (1883-4). Rain only 

 occurs during parts of the year; South California 

 would be practically rainless were it not for the 

 southern deflection of the paths of some of the 



