404 



NATURE 



[May 26, 192 1 



to make the assertion that implements of Mousterian 

 or Acheulaean or Chellaean or pre-Chellaean work- 

 manship were not manufactured or in use when 

 Eoanthropus flourished. Assuredly we are not in a 

 position to assume either that Eoanthropus manu- 

 factured flint implements, or, on the other hand, that 

 he did not do so. To me it seems improbable that 

 Eoanthropus had anj-thing to do with flint imple- 

 ments at all, although more likely that he suffered 

 from them rather than that he benefited by their use." 



In an article on the conditions of cellular im- 

 mortality {Sci. Monthly, vol. xii., No. 4, p. 321) Prof. 

 Raymond Pearl discusses artificial parthenogenesis 

 and tissue culture and the views regarding senescence 

 to which tlpey lead. The life of the unfertilised egg- 

 cell can be prolonged only by fertilisation or by some 

 other stimulus to development. The experiments of 

 Leo Loeb, Harrison, Burrows, Carrel, and others 

 in the culture not only of embryonic, but also of adult, 

 tissues in vitro show that the phenomena of senes- 

 cence do not originate in the cells themselves; for 

 all the essential body-tissues, including heart-muscle, 

 nerve-cells, spleen, connective tissue, and kidney -cells, 

 have been shown to be capable of multiplication in- 

 definitely by mitotic division outside the body. With 

 improved methods Carrel has kept a strain of con- 

 nective tissue from the chick's heart alive and grow- 

 ing for nine years. There is, therefore, a potential 

 immortality not only of germ-cells, but also of tissue- 

 cells, and senescence is a phenomenon of the dif- 

 ferentiated body as a whole, due to the effects of the 

 various types of cells upon each other. 



In the Journal of the Quekett Microscopical Club 

 (vol. xiv., November, 1920) Mr. G. T. Harris describes 

 the Desmid flora of a small area in East Devon, and 

 compares it with that of Dartmoor in order to elucidate 

 the influence of geological beds on the species density 

 of the Desmid flora. Dartmoor is a Palaeozoic, semi- 

 mountainous area of extensive peat deposits, great 

 rainfall, and deep bogs; the other, a Triassic, low- 

 land area, with no peat-bogs, moderate rainfall, and 

 unimportant bogs. The numerical results from each 

 area were surprisingly similar, indicating that the 

 factors influencing the richness or poverty of 

 Desmid floras must be sought elsewhere than in the 

 geological beds upon which the habitats stand; and 

 a recent investigation of the Desmid flora of a dis- 

 trict on Eocene beds confirms this statement. The 

 species density of the two districts is also practically 

 the same. A systematic list of the species and varie- 

 ties from the Triassic area, 429 in number, is given. 

 This adds 122 forms to the Desmid flora of Devon- 

 shire, bringing it up to a total of about 500 species 

 and varieties. From gatherings made during the 

 winter it would appear that most species in a southern 

 county like Devon pass the winter in the vegetative 

 state. 



The Forestry Commission in a recent report states 

 that up to April it had acquired for planting 

 97,160 acres of land, of which 36,682 acres are in 

 England and Wales, 54,972 acres in Scotland, and 

 5506 acres in Ireland. The area of 1586 acres 

 NO. 2691, VOL. 107] 



planted under favourable conditions in 1919-20 con- 

 tinues to show satisfactory growth. During the 

 1920-21 season 6257 acres were planted at seventeen 

 centres in England and Wales, nine centres in Scot- 

 land, and twelve centres in Ireland, while new nur- 

 series have been established in various parts of the 

 country. The Commission has published a report 

 of the British Empire Forestry Conference held in 

 London last July, which can be obtained through any 

 bookseller or from H.M. Stationery Office (75. 6d.). 

 Leaflets on forest pests — No. 2, Chermes Cooleyi; 

 No. 3, The Pine Shoot Beetle ; and No. 4, Hylastes 

 ater — can be obtained free on application to the Com- 

 mission at 22 Grosvenor Gardens, London, S.W.i. 



The disposal of the debris from hydraulic mining 

 and its influence on the lower courses of rivers have 

 been urgent problems in California for the last half- 

 century. A monograph on the subject by the late 

 Dr. G. K. Gilbert is published by the United States 

 Geological Survey entitled " Hydraulic Mining Debris 

 in the Sierra Nevada " (Professional Paper 105). The 

 material washed from the hillsides is carried by the 

 creeks and rivers, and eventually finds lodgment in 

 the lower reaches of the streams and during floods on 

 the riparian lands, thus doing a considerable amount 

 of harm to navigation and agriculture. For these 

 reasons hydraulic mining has been severely restricted 

 for many years. The bays of the San Francisco 

 system have been sounded and mapped more than 

 once, and comparisons made between early and recent 

 maps show that \he areas of the bays have been 

 much reduced by the seaward growth of muddv 

 shoals. Since the discovery of gold and the beginning 

 of hydraulic mining more than 1,000,000,000 cubic 

 yards of material have been deposited in the various 

 bays. Dr. Gilbert made careful researches on the 

 effect of this shoaling and diminution of area on the 

 tidal currents and depths of water on the Golden 

 Gate bar. The crest of the bar shows a retreat 

 towards the land, but no reduction in depth since 

 1855, ^"d the navigability of the bar has apparently 

 not yet been affected. 



In the Journal of the Franklin Institute for April 

 Mr. A. H. Armstrong considers the economic aspects 

 of railway electrification in the United States. He 

 points out that at the present time we are facing 

 the facts of an eight-hour working day with overtime 

 costing 50 per cent, more, greatly increased wages, 

 fuel prices at levels never before reached, and main- 

 tenance costs at almost prohibitive values. With no 

 immediate prospect in sight of any material reduc- 

 tion in the price of labour, its output must be in- 

 creased, and electric operation effects this both on 

 the railway line and in the workshop. The elec- 

 trification of railways is a very costly operation, but 

 the saving in operating expenses enables a reasonable 

 return to be obtained on the capital expended. The 

 argument for electrification, however, rests on a 

 broader foundation than this. The national prosperity 

 of America is bound up with the future growth of 

 its transport system, and this growth depends on the 

 adoption of electrification. An incidental advantage 

 of electrification is that it would save one-sixth of all 

 the coal mined in the United States. 



