390 



NA TURE 



Sept. 12, 1872 



than in discovoring a remedy for the Potato Disease. 

 The questions which would present themselves for 

 solution in such an inquiry are numerous. It would not be 

 difficult to collect the facts ; but they have never yet been 

 tabulated or presented to the public in such a form that 

 any conclusions can be drawn unquestionably from them. 

 A competent authority on these subjects, the Gardcnei\', 

 Chronicle, recently remarked : — " Though for nearly a 

 quarter of a century, more or less, cultivators have had j 

 to wince under the losses inflicted by the enemy, they 

 have not yet learnt either the mode of invasion or the 

 method of destruction." The Commission would have to 

 inquire whether the disease is most prevalent on any 

 particular soil ; whether, as some assert, seed left in 

 the ground through the winter enjoys comparative 

 immunity as contrasted with that sown in the 

 spring ; whether seed introduced from a distance is safer 

 than that grown in the neighbourhood ; whether old 

 varieties are dying out and new ones comparatively 

 healthy ; whether, if the disease can by any means be 

 warded off till August 10, the crop is then comparatively 

 safe, and very many others, on which every diversity of 

 opinion exists at present .'' On one point almost all 

 authorities are agreed, viz., that the disease generally 

 makes its first decided appearance during thundery 

 weather. The exceptional amount of electrical dis- 

 turbance which extended over almost the whole country 

 during July of the present year appears to have been 

 most unfavourable to the potato crop ; while a clergyman, 

 writing from a district where thunderstorms are remark- 

 ably rare, in the portion of the county of Devon to the 

 south of Dartmoor, averaging about six in twelve years, 

 states that it is there almost free from disease. 



It is worthy of note that an unusual development of the 

 potato blight has been hitherto accompanied by murrain 

 or epidemic diseases in animals and in other crops, and 

 that a certain periodicity appears to be manifested.. The 

 present year has witnessed the most virulent outbreak 

 since 184.6 ; tlie worst of the intermediate years were 

 nearly midway, from 1859 to 1S61, showing an approxi- 

 mate recurring interval of about twelve years. A writer 

 in the Gardcncfs Chronicle thus describes the crops in 

 the latter year : — " My potatoes are in as bad a state as I 

 ever remember to have seen them ; my turnips are rapidly 

 rotting, and many are idled with a semi-fluid offensive 

 matter ; the lettuces in various parts of the kitchen- 

 garden are nearly all rotten ; the roots are found generally 

 diseased ; the cabbages, savoys, and others of the Drassica 

 are what gardeners term blind ; the beans are spoiled by 

 the black fly ; the peas arc all more or less blighted or 

 mildewed ; many of the plum and cherry trees are 

 destroyed ; I never witnessed anything more lamentable 

 and disheartening." Other accounts agree in the main 

 with this, at least as regards the potatoes in that year. 

 Now, it is very remarkable that .an interval of from eleven 

 to twelve years coincides with the period of maximum 

 sun-spots. The present time is near the maximum of sun- 

 spots, so was i860, so was 1848, the curve showing but little 

 decline for one or two years on each side of the actual 

 maximum. Now, if it can be shown that epidemics like 

 the potato blight are connected with great cosmical 

 cycles, an important step is gained. Physicists are now 

 nearly of accord that a connection exists between the sun- 



spot period and the recurrence of electrical and other 

 disturbances in the earth's atmosphere. It may be urged 

 that such a conclusion as this would make cure hopeless, 

 and paralyse, instead of stimulating, energy, by inducing 

 a kind of hopeless fatalism. Not at all. An evil which can- 

 not be avoided may, nevertheless, be greatly mitigated by 

 scientific knowledge and skill. To be forewarned is to be 

 forearmed, and a knowledge of the cause of a disease is 

 already halfway towards its cure. If we were certain that in 

 another twelve years we should be liable to a recurrence 

 of the blight with unusual severity, the farmers might be 

 persuaded to plant only so much as would be likely to 

 yield seed for the next year, and that only under the most 

 favourable circumstances, where comparative immunity 

 might be predicted ; and large breadths might be devoted 

 to turnips, beet, or other root-crops which experience 

 showed to be likely to yield good results, and which 

 would furnish some substitute for the lost potato. 



We have endeavoured to sketch out only a few of the 

 questions which would present themselves for solution 

 were we in earnest to institute a thorough scientific in- 

 vestigation of the cause and cure of the potato blight, 

 and to point [out that few subjects are more worthy the 

 attention of a commercial and practical nation. 



SHARPE ^.- DRESSER'S BIRDS OF EUROPE 



The Birds of Eiiro/e. By P. B. Sharpe and H. E. 

 Dresser. i\arts xi. and xii. (Published privately. 1 



''I^HE completion of the first volume of this important 

 -1- work by the issue of Parts xi. and xii., affords 

 the authors an opportunity of expressing their deter- 

 mination to continue the monthly issue with as much 

 punctuality as is compatible with the fulness and accuracy 

 at which they aim. This volume has occupied eighteen 

 months in its publication ; but as it contains lol coloured 

 plates and about Soo or goo pages of letterpress of large 

 quarto size, the wonder is rather that so near an approach 

 to regularity has been attained in a work which is taking 

 so much larger dimensions than was at first anticipated. 



The present parts show no lack of the energy and care 

 hitherto exhibited. In addition to the seventeen species 

 figured and copiously described, we have three additional 

 plates with eight figures of the Sparrow Hawk in 

 various states of plumage, and two others with additional 

 figures of the Ring Ouzel and the Rock Thrush. As an 

 example of the great care bestowed by the authors in the 

 accumulation and critical comparison of specimens from 

 all parts of Europe, and from other quarters of the world 

 where necessary, we may state that the present part dis- 

 criminates between several birds that have hitherto been 

 confounded, and thus adds two species to the list of 

 European birds, and one to that of Britain. A fine 

 Woodpecker {Pic/ts lil/ordi), found in Greece and Turkey, 

 has been separated from Pictis Icncoiiolus which inhabits 

 the more northern parts of Europe ; while the British 

 form of the Cole Tit {Parus atcr) is found to be so con- 

 stantly different from that which inhabits the Continent 

 as to require a distinct specific name, and it h^s accord- 

 ingly been called Parus byHta)!icus. To illustrate these 

 minute specific differences the excellent plan is adopted of 

 giving figures of the allied species on the same plate. 



