4o6 



NATURE 



[December 9, 1915 



parasitic fungi belonging to the family Peronospor- 

 accae, of which perhaps the most widely known is the 

 ix)tat()-blight fungus, Phyiophthora infestans. A list 

 of liftiiin species is given in which this hibernation 

 occurs, the necessary evidence being supplied by the 

 author himself for four of them. In the second paper 

 evidence is adduced to show that the source from 

 which the potato-blight originates each season is to 

 be found in aerial shoots of the potato, which become 

 infected with the mycelium of the fungus direct from 

 the diseased tuber. From nearly a thousand diseased 

 tubers specially planted during the seasons of 19 13 

 and 1914 five cases arose where one or more diseased, 

 spore-bearing shoots were produced, and four of them 

 served as centres from which the blight spread to 

 neighbouring, healthy plants. That this might occur 

 was shown by de Bary over half a century ago, but, 

 although confirmed later by Jensen, it cannot be said 

 that this view of the mode of infection of the crop 

 has met with universal acceptance. Mr. Melhus's 

 work, therefore^ — carried out under field conditions — 

 provides a further and substantial measure of support 

 for the original view propounded by de Bary. 



In the annual report of the Sniiths.onian Institution 

 for 19 14, Mr. E. N. Marais has an account of the 

 drought in Watersberg, South Africa. The name was 

 originally given as expressive pf the fertility of that 

 part of the Transvaal. To-day it is practically a desert 

 with dried-up watercourses, dead orange groves, and 

 desolate pasture lands. The game, once very plenti- 

 ful, has almost all left the district, and little animal 

 life remains. Only the numerous thermal springs 

 remain unaffected, and on these the few inhabitants 

 depend for drinking water and for irrigation. 



The pastoral and agricultural possibilities of Central 

 Australia have been a good deal discussed in recent 

 years. Attention was directed to them at last year's 

 Australian meeting of the British Association. The 

 probable value of the region to the north-east of Kal- 

 goorlie and Laverton is indicated in a paper by Mr. 

 A. C. Macdonald in the Victorian Geographical Journal 

 (vol. xxxi., part ii.). Mr. Macdonald brings together 

 evidence from explorers and others to show that the 

 rainfall, though most irregular, is by no means absent, 

 but that the soil would be most productive under a 

 proper system of irrigation. This, he contends, would 

 be feasible, since artesian water in quantities has been 

 proved to exist near the surface. There is every indi- 

 cation that this water is quite suitable for irrigation, 

 and is not heavily charged with alkali. 



The United States Geological Survey is publishing 

 a series of four geographical handbooks for travellers, 

 each book covering one of the chief railway routes 

 west of the Mississippi. The second one deals with 

 the Union Pacific route from Omaha to San Fran- 

 cisco (Bulletin 612, The Overland Route, price i dollar). 

 The idea is excellent, and is admirably carried out. 

 Much geographical information otherwise difficult of 

 access is collected, and many historical details are 

 added. The illustrations are good, but the chief 

 feature of the volume is the series of twenty-five con- 

 tour maps on a scale of i to 500,000. They are clear 

 and well printed, and free from crowding of detail, 

 NO. 2406, VOL. 96] 



yet contain all that a traveller could desire. Each map 

 is conveniently placed for reference from the text. The 

 book has much value even for those who do not 

 contemplate going the journey. 



The Canadian Department of Mines has issued a 

 very interesting monograph (Memoir No. 78) on the 

 I Wabana iron ore of Newfoundland, by Mr. A. O. Hayes. 

 I These famous iron-ore deposits form a number of 

 I beds, which outcrop for about three miles along the 

 northern shore of Bell Island, Conception Bay, and 

 dip to the north-west under the waters of the bay. 

 These beds form part of an extensive series of Ordo- 

 vician sedimentary deposits, mainly of sandstones and 

 shales, comprising the higher beds of the northern 

 limb of a somewhat flat anticline. The upper 

 1000 ft. of this series contain a number of ferriferous 

 beds, two of which, known as the " Dominion Bed " 

 and the "Scotia Bed," are of workable thickness, 

 the former averaging about 10 ft. and the latter, 

 the upper one, about 8 ft., though thicknesses up to 

 30 ft. have been met with. The total quantity of iron 

 ore is estimated at more than 3000 millions of tons. 

 The ores consist mainly of* red haematite, together 

 with chamosite (aluminous ferrous silicate), and side- 

 rite. The ore is oolitic in structure, the spherules con- 

 sisting generally of alternate concentric layers of the 

 two first-named minerals, though some consist wholly 

 of haematite. Fragments of fossil shells occur 

 throughout the ore, and it is to their presence that the 

 phosphoric acid in the ore (usually 1-5 to 2-5 per cent.) 

 is due. The author considers these ores to be primary 

 deposits formed in shallow seas, and holds that "the 

 iron was derived by long-continued weathering of 

 earlier crystalline and sedimentary rocks, the solution 

 of their iron content by mineral and vegetable acids 

 and subsequent transportation of the iron salts by 

 streams into the sea." He holds that the evidence 

 is against the probability of these ores having been 

 formed by the metasomasis of an original oolitic lime- 

 stone. 



The rainfall over the British Isles for October is 

 dealt with in Symons's Meteorological Magazine for 

 November, and the rainfall table gives the tentative 

 results of the British Rainfall Organisation prior to 

 the publication of fuller details in the rainfall volume 

 for 19 15. There were only three stations in Great 

 Britain with an excess of rain — Rousdon having 190 

 per cent, of the average, Stroud 121 per cent., and 

 Braemar 103 per cent. Arncliffe, in Yorkshire, had 

 only 21 per cent, of the average rainfall, and was 

 relatively the driest place in the kingdom ; Seathwaite 

 had 26 per cent, of the average, and Hull 31 per cent., 

 whilst other places had more than 33 per cent. The 

 greater part of Ireland was wet, but the fall at Omagh 

 was only 82 per cent, of the average, while it was 

 as high as 179 per cent, at Waterford, and 155 per 

 cent, at Gorey, Wexford. Less than one-half of the 

 average rainfall for the month is said to have fallen 

 over the west and north-west of Scotland and over 

 the northern half of England and Wales. The map 

 for the Thames Valley shows a considerable range in 

 the rainfall, the measurement for the month amount- 



