4io 



MATURE 



\Sept. 19, 1872 



a most important service to practical agriculture by the 

 institution of a series of crucial experiments in its ex- 

 perimental grounds at Chiswick. 



Dr. Hooker's statement that the starch of the diseased 

 potatoes is not affected by the parasite, but retains its 

 nutritive properties, is wortliy of more attention than it has 

 yet received. He recommends rasping the p ;elcd tubers 

 upon a grater into a tub of cold water. In a few minutes 

 the starch will be found to have sunk to the bottom, and 

 the dise.ised matter, woody fibre, &c., wiU be suspended 

 in the water, and should be poured away with it. Fresh 

 water should then be added, the starch stirred up, and 

 again allowed to settle. Two or three of such washings 

 will remove all impurities, and render the starch fit for 

 use. If thoroughly dried it will keep for any time, and 

 can be used as arrowroot for puddings and cakes, and for 

 mixing with flour as bread. This plan is open to obvious 

 objections, both from its tediousness, and from the fact 

 that when the disease has made any considerable 

 progress, the smell is so offensive as to render both 

 the peeHng and the grating alike impossible to 

 those possessed of ordinary olfactory perception. Dr 

 Hooker, however, states that the plan was suc- 

 cessfully pursued in 1845 and 1S46 by the villagers of 

 Hitcham under the direction of the late Rev. Prof. Hens- 

 low ; and it seems incredible lliat chemical science should 

 be unable to devise some practical and economical method 

 for separating a wholesome subsiance of such enormous 

 value in the bulk from the noxious ingredients. 



Although the immediate cause of t'ue potato disease has 

 been clearly determined, as has been stated above, to be 

 the attacks of a parasitic fungus, yet we are by no means 

 prepared to agree with the conclusion of a distinguished 

 writer,* that it " seems quite absurd, when the whole 

 rationale of the potato diseas.- has been so carefully ex- 

 plained, to look for an explanauon in mere climatic con- 

 ditions, e.xhaustion, weakness of constitution, or any of 

 the empirical causes which are so often brought forward." 

 The Peroiwspora is undoubtedly the proximate cause of 

 the disease ; for the ultimate cause we may have to look to 

 a very different set of circumstances. It is probable that 

 many epidemic diseases, both of men, animals, and plants, 

 are caused by parasitic fungi ; yet the attacks of the para- 

 site may be favoured by special climatal or other con- 

 ditions. We know that many animal plagues can be 

 absolutely eradicated by the removal of the conditior;s 

 which favour the propagation of the pest. The idea hinted 

 at in our article last week that epidemic diseases may be 

 expected in periodically recurring cycles is at least one 

 deserving further investigation, and is supported by some 

 curious facts. No reason lias been given why the potato 

 blight should have broken out so violently in 1845, when 

 we had experienced before that many as ungenial summers 

 during which it did not make its appearance, nor why it 

 should have appeared simultaneously in so many remote 

 countries — in St. Helena and Canada as virulently as in 

 Europe — where the climatal conditions are altogether 

 different ; i860 and 1872 are also not the only wet and 

 thundery summers we have known during the last 

 twenty years. It is quite possible that cosmical condi- 

 tions may at definite intervals favour the disease, but that 

 it may be developed only when certain other special con- 



» Kev. M. J. Berkeley, ill Cudnicrs Chronicle, Nov. 4, i8;i. 



ditions co-operate with these. We refer in another 

 column to the systematic investigation now being carried 

 on in France and Portugal as to the cause of the vine 

 disease. 



The period of maximum sun-spots of between eleven 

 and twelve years, as shown by the researches of De La 

 Kue, .Stewart, and Loewy, falls in 1848, i860, and 1872 ; 

 and it is very singular that history seems to point to 

 nearly the same approximate period for great national 

 epidemics. Thus, according to Hecker's " Epidemics of 

 the Middle Ages," the dates of the five great visitations 

 of the sweating sickness in this country were 1485, 1506, 

 15 17, 1528, and 155 1, the epidemic being accompanied on 

 almost every occasion by other pestilences in man and 

 beast in this and other countries, or by general failure of 

 crops. We have, of course, no means of ascertaining 

 the condition of the surface of the sun during those years ; 

 but it is at least a singular coincidence that 29 cycles of 

 in years bring us from 155 i to 1872. 



We do not wish to lay more stress on these curious 

 facts than they deserve, but simply to indicate the number 

 of points of view from which the subject may be investi- 

 gated. To have ascertained accurately the immediate 

 cause of the potato disease is no doubt a great step 

 gained ; but the scientific method -will not allow us to stop 

 here. We must do our best to penetrate further into the 

 arcana of Nature, and bring all the resources of Science 

 to bear to investigate the conditions which appear to 

 favour the appearance and spread of the invader, and the 

 means which promise the greatest chance of success to 

 repel his attacks. 



GLADSTONE'S LIFE OF FARADAY 

 Miduicl Faraday. By J. H. Gladstone, Ph.D., F.K.S., 

 &c. (London : Macmillan and Co., 1872.) 



THERE can be no doubt that a life of Faraday suit- 

 able for the general public was mucli needed. 

 Dr. Bcnce Jones's work, though full of interest to scien- 

 tific men, and to those who knew Faraday personally, was 

 too voluminous and too lacking in^cohesion to be very widely 

 re.ad. Dr. Tynd.all's brilliant sketch fascinated the reader 

 with the scientific aspect of the life it recorded, but left 

 one longing to know " the inner supplement to that noble 

 ouUvard life" of Faraday. Dr. Gladstone's memoir very 

 largely meets the wants wc express. 



There are few men better fitted to write a life of Fara- 

 day than Dr. Gladstone. Not only was he the personal 

 friend of Faraday, associated with him in the manage- 

 ment of the Royal Institution, and in scientific inquiries 

 connected with the Trinity House, but, what is more 

 important, their pursuits and sympathies ran in nearly 

 parallel paths. And so with a loving hand Dr. Gladstone 

 has gathered the materials for his memoir. These are 

 drawn only to a small extent from sources with which we 

 are already familiar, for the author gives us the benefit of 

 his own recollections, and also numerous incidents from 

 the many private sources of information to which he has 

 had access. A delightful freshness and personal interest 

 are thus given to tlie narrative. Here, for example, is 

 an anecdote that will be new to most of our readers, and 

 which illustrates the quiet humour which Faraday possessed 

 One evening at the Royal Institution, when a lecture on 



