296 



NATURE 



[January 30, 1902 



and their position thereon. The proofs here given should 

 serve to ekicidate some of the puzzHng cases not infre- 

 quently met with in testing errors of refraction. 

 Chapter x., again, gives much valuable information on the 

 use of the ophthalmoscope to the best advantage, and 

 the difficulties of rctmoscopy are sufficiently dealt with in 

 the last chapter. There is no mention of accommodation 

 or presbyopia, several points in which might well have 

 been touched upon. An index would have been of 

 assistance in the search for any equation relating to a 

 particular case. 



The Process Year Book, 1901-2. Edited by William 

 Gamble. Pp. xvi-fi52. (London: A. W. Penrose 

 and Co., 1901.) 



Every year we receive this admirable and beautiful 

 book illustrating the present state of process work, and 

 we cannot do better than again suggest that everyone 

 interested in the art of picture reproduction should be 

 the possessor of this volume. The illustrations and text 

 still maintain their high standard of excellence, and 

 the variety of the subjects and processes dealt with gives 

 the reader a good insight into the manifold methods in 

 photo-mechanical engraving and the allied arts and 

 crafts. 



It may, perhaps, be specially mentioned that in con- 

 sequence of the great advance in the department of 

 process work relating to the three-colour method the 

 editor has introduced a variety of specimens such as 

 perhaps never before has been collected together between 

 the covers of a single book. A glance at these soon 

 suffices to illustrate the high state of efficiency of the 

 methods employed to-day ; and one only wonders what 

 the future has in store for us, since it is to this branch of 

 process woik that we look for the possibility of the 

 greatest progress. 



Nautical Aslrotwiny. By J. H. Coh in, B.A. Pp. 127. 

 (London : E. and F. N. Spon, Ltd., 1901.) Price 

 zs. bd. net. 



One of the greatest difficulties encountered in the study 

 of spherical and nautical astronomy is to obtain a proper 

 comprehension of the various circles of the celestial 

 sphere, without which the solution of the problems in- 

 volved can never be anything more than mechanical. 

 The author of this book, however, has not thought it 

 necessary to assist the student greatly in this direction, 

 for fifty very brief definitions can by no means be regarded 

 as an adequate introduction to celestial geometry. Thus, 

 unless the student is endowed with an exceptionally 

 good geometrical imagination, or has the advantage of a 

 good teacher, it does not seem likely that he will be able 

 to use the book with profit. The initial difficulties ex- 

 cepted, however, the book has many good features ; the 

 explanatory matter is brief and clear, and there is a useful 

 collection of formuhi?, rules, numerical illustrations and 

 exercises to be worked out. Much space is saved by 

 the omission of tables which do not vary, while specimen 

 pages of the " Nautical Almanac," adapted to the exer- 

 cises, have been introduced. 



The book is designed to cover the elementary and 

 advanced stages of the South Kensington syllabus, and 

 also includes the course for "extra master" in the Board 

 of Trade examination. 



Elementary Chemical Theory. By G. H. Martin, M.A., 

 F.C.S. Pp. 24. (London: Rivingtons, 1902). Price yi/. 



The only use to which this collection of didactic state- 

 ments can be put is to furnish students of chemistry with 

 material suitable for copying into their notebooks. It 

 was scarcely worth while to attempt to extend the use of 

 the book beyond the author's own pupils. 



NO. 1683, VOL. 65] 



LETTERS TO THE EDITOR. 



[ The Etlilor does iiol hold himself responsible for opinions ex- 

 pres<ied liy his correspondents. Neither can he undertake 

 to return, or to (oi respond with the -writers of, rejc<lti 

 manuscripts intended for this or any other part of NatUKE. 

 No notice is taken of anonvmous contniunications.'\ 



Cherry Disease. 



In Nature for January 9 (p. 239) there is a report of the 

 meeting of the Royal Microscopical Society on December 18. 

 The president, Mr. William Carruthers, F. K.S., made a com- 

 munication with respect to the cherry disease which has appeared 

 in Kent, from which I extract the following : — 



" The results of experiments in the cultivation of the fungus 

 showed it to he one which belonged to the genus Gnomonia. 

 Many of the fungi in this class passed through various stages in 

 their lifehislory, for example the mildew on wheat, which was 

 first developed on the berberry and then spread to the wheat, 

 appearing first as rust and aflerwards as mildew from the same 

 mycelium. The president referred to the absence in this 

 country of any aulhority competent to investigate cases such as 

 this: on the continent, however, the Governments had taken 

 up the matter, and the experts who had inquired into it had 

 found that to check the spread of the disease it was necessary 

 to collect all the dead leaves and hum them." 



Prof. A. W. Bennett followed in the same strain and 

 " enlarged upon the absence in this country of investigations 

 into such matters by State-paid establishments, and described 

 what was being done in the United States, where every State 

 had its own experimental station." 



Now it is not my intention to discuss whether the Govern- 

 ment does as much for scientific inquiry in the interests of the 

 community as it might do. But it is clear to nie that nothing is 

 gained by overstaling the case. There are two "Slate-paid" 

 establishments devoted to botany in this country, Kew and the 

 Botanical Department of the British Museum. Each happens 

 to have upon its staff an officer trained in mycological investi- 

 gation. And it may be added that Mr. Carruthers is himself 

 consulting botanist to the Royal Agricultural Society. 



So far as Kew is concerned, the matter was promptly dealt 

 with in ordinary routine. Mr. Massee, who has charge of the 

 cryptogamic colleclions, had given a brief account of the 

 disease in his "Text-book of Plant Diseases," with a figure 

 (pp. no. III), although at the time (1899), so fat as lamawarc, 

 the disease had not been noticed in this country. Mr. A. O. 

 Walker, of Maidstone, sent specimens in November, 1900. I 

 quote the Gardeneri' Chronicle for May 23, 1901 (p. 191), where 

 he writes : — 



" Early in November I sent specimens to Mr. G. Massee, 

 of the Kew Herbarium, who reported to me that the leaves 

 were affected by the fungus Gnomonia crythrostoma, and 

 quoted Frank's opinion that the leaves should be gathered and 

 liurnt." 



The council of the Royal Agricultural Society issued on 

 February 6, 1901, a report by Mr. Carruthers giving the history 

 of the disease and recommending Frank's remedy of burning 

 I he leaves. There is nothing very profound in this recom- 

 mendation, as it is a general method applicable to all plant dis- 

 eases propagated by spores, and aims at removing the source of 

 infection. 



As I recently pointed out in Naturf. (vol. Ixiv. p. 212), 

 we owe to the late Prof Cornu "the principle now so 

 familiar as to seem almost obvious, of preventive treatment by 

 the careful destruction by burning of the di'bris of plants which 

 may harbour spores." 



I may add that the Gnomonia is well known to mycologists, 

 having, in fad, been first described by Persoon as a Sph;);ria a 

 century ago, and there are in the Kew Herbarium specimens of 

 it from no less than eight published collections. Mr. Carruthers 

 in his report, which is reproduced in the Journal of the Royal 

 Horticultural Society (n.s. xxv. pp. 313-316), does not give an 

 illustration of the Gnomonia, hut figures instead a " Fragment 

 of Leaf of Cherry Tree showing groups of Parasitic Fungi." 

 These belong, apparently, to a species of Phoma and, .so far as 

 I am aware, there is no evidence that they have anything to 

 do with the Gnomonia. 



There the matter stands, and for my part I entirely fail to see 

 how " the authority competent to investigate cases such as this ' 

 of whom we are said to be in want, could carry it farther. The 



