360 



NATURE 



[December 4, 1919 



infected there is no hope of saving the tree. The 

 disease has been proved to occur on a number of 

 plants besides plum, apple, and other members of 

 the family Rosaceae, including species of laburnum, 

 horse-chestnut, and cultivated varieties of gooseberries 

 and currants. As a preventive measure good cultiva- 

 tion is recommended ; careless pruning, unsatisfactory 

 drainage, and deficiency of lime are especially to be 

 avoided. The author also indicates an apparently dis- 

 tinct disease which he calls "false silver-leaf," which 

 may be mistaken for the disease caused by Stereum, 

 but no trace of this fungus has been found in the 

 plants affected. It is suggested that false silver-leaf, 

 from which plants recover under careful treatment, is 

 due to physiological weakness. It has been observed 

 in cultivated varieties of apple, cherry, peach, and 

 plum. 



.A NOTEWORTHY addition to our knowledge of Eocene 

 foraminifera is made by the publication of the late 

 Mr. E. Halkyard's "Fossil Foraminifera of the Blue 

 Marl of the Cote des Basques, Biarritz," under the 

 care of Messrs. E. Heron-.'Xllen and A. Earland (Mem. 

 Manchester Lit. and Phil. Soc, vol. l.xii., part ii.). 

 Megalospheric and microspheric forms are discussed 

 among the nummulites. 



Messrs. F. F. Grout and T. M. Broderick {Amer. 

 Jotirn. Sci., vol. xlviii., p. igg, 1919) describe struc- 

 tures in the Huronian iron-bearing strata of the 

 Mesabie range in Minnesota as due to algaj. In thi.s 

 they have the support of Dr. C. Walcott, who writes 

 that the iron-ore was evidently separated out of marine 

 waters through the metabolism of the algal growths, 

 which he compares with Cryptozoon. 



I.v the American Journal of Science (vol. xlviii., 

 p. 136, 1919) Prof. R. A. Daly replies to recent 

 criticisms of his "glacial-control" theory of the growth 

 of coral-reefs. He urges that the general absence of 

 cliffs on the island spurs may be due to the protec- 

 tion afforded by rapidly growing fringing reefs in late 

 Cainozoic time ; these would have to be scoured- away 

 before the Pleistocene sea could attack the volcanic 

 masses. Variations in the depths of lagoons, again, 

 may be expected even on a general platform of' erosion, 

 owing to the presence of drowned valleys, fault- 

 troughs, and volcanically formed depressions not vet 

 filled with detritus. Lagoon depths greater than 

 50 or 60 fathoms are, however, rare. 



The Times of November 28 contains an article 

 from Prof. Einstein on his generalised principle of 

 relativity. Prof. Einstein remarks at the beginning 

 of the article : " After the lamentable breach in the 

 former international relations existing among men of 

 science, it is with joy and gratefulness that I accept 

 this opportunity of communication with English astro- 

 nomers and physicists. It was in accordance with 

 the high and proud tradition of English science that 

 English scientific men should have given their time 

 and labour, and that English institutions should have 

 provided the material means, to test a theory that had 

 been completed and published in the country of their 

 enemies in the midst of the war." After a brief 

 account of the general nature of the theory, which 

 does not add anything to what has been summarised 

 by Prof. Eddington in his report to the Physical 

 Society, Prof. Einstein concludes : " The great attrac- 

 tion of the theory is its logical consistency. If any 

 deduction from it should prove untenable, it must be 

 given up. A modification of it seems impossible with- 

 out destruction of the whole. No one must think 

 that Newton's great creation can be overthrown in 

 any real sense by this or any other theory. His clear 

 and wide ideas will for ever retain their significance 

 NO. 2614, VOL. 104] 



as the foundation on which our modern conceptions 

 of physics have been built. . . . By an application of 

 the theory of relativity to the taste of readers, to-day 

 in Germany I am called a German man of science, 

 and in England I am represented as a Swiss Jew. 

 If I come to be regarded as a bele noire, the descrip- 

 tions will be reversed." Prof. Eddington, in the 

 Contemporary Review, quotes from Newton's 

 "Opticks": — "Query i. Do not bodies act upon 

 light at a distance, and by their action bend its rays? " 



O.N' Engler's theory of the origin of petroleum, the 

 oil has been formed out of animal and vegetable fatty 

 matters derived from marine animals and plants. 

 The fats have been hydrohsed by water, and the 

 resulting fatty acids, under the influence of heat and 

 pressure, have then been decomposed into carbon 

 dioxide and hydrocarbons, these latter constituting 

 the petroleum. Whilst this theory would account for 

 the liquid hydrocarbons of the aliphatic series found 

 in petroleum, it does not explain the presence either 

 of solid paraffins or of the aromatic (naphthenic) 

 hydrocarbons which are found in most petroleums, 

 and, indeed, form the whole of some varieties. 

 Engler's distillation experiments in confirmation of 

 the theory were made chiefly on free oleic and stearic 

 acids. It is probable, however, that salts of these 

 acids, rather than the free acids themselves, would 

 be the bodies acted upon during the natural produc- 

 tion of petroleum. Following up this idea, MM. 

 Pictet and Potok have carried out a series of experi- 

 ments on the distillation of sodium stearate and 

 sodium oleate, with the view of ascertaining whether, 

 in operations thus approximating more closely to the 

 natural conditions, aromatic hydrocarbons or paraffins 

 of high boiling points are produced (Helvetica Chiniica 

 Acta, 2, v., 501). In the result it was found that 

 the chief products were acyclic and unsaturated hydro- 

 carbons closely agreeing with those found in American 

 petroleum, but no trace of naphthenic (aromatic) 

 hydrocarbons was produced. Hence the origin of 

 Baku petroleum, and of the numerous other kinds 

 which contain these naphthenic bodies, is not ac- 

 counted for by Engler's theory. Further, since many 

 of these bodies show optical rotation, they have prob- 

 ably been produced at relatively low temperatures, and 

 not by the closing up of acyclic compounds, which 

 would demand high temperatures and yield inactive 

 products. No likely source of such optically active 

 bodies suggests itself except the resinous or terpenic 

 constituents of the higher plants. Similar compounds 

 have, in fact, been extracted from coal. For the 

 numerous petroleums containing both acyclic and 

 naphthenic hydrocarbons a twofold origin appears to 

 be indicated. 



The announcements of Messrs. A. and C. Blai 

 Ltd., include "X-rays in General Practice," Alice 

 Vance Knox, with chapters on Instrumentation, Dr. 

 R. Knox; " Cerebro-Spinal Fever: The Etiology, 

 -Symptomatology, Diagnosis, and Treatment of Epi- 

 demic Cerebro-Spinal Meningitis," Drs. C. Worster- 

 Drought and A. M. Kennedy; "Medieval Medicine," 

 J. J. Walsh; and "The Making of Europe: A 

 Geographic Treatment of the Historic Develop- 

 ment of Europe," W. H. Barker And W. Rees. 

 In addition to the books announced for publication 

 by the Cambridge University Press (see Nature, 

 November 20, p. 321) mav be mentioned "Physics," 

 Dr. Norman R. Campbell, 3 vols.; "The Theory of 

 the Imaginary in Geometry," J. L. S. Hatton ; " Prac- 

 tical Chemistry for .Agricultural Students," H. .\. D. 

 Neville, vol. i. ; "What Became of the Bones of St. 

 Thomas," Rev. Canon .\. J. Maron ; " From Ritual 

 to Romance" (.\ Study of Comparative Religion and 



