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THURSDAY, OCTOBER 23, 18S4 



FIELD AND GARDEN CROPS 

 Diseases of Field and Garden Crops. By Worthington 

 G. Smith, F.L.S. (London : Macmillan and Co., 

 1884.) 



THE fact that a handbook of the diseases of crops has 

 been written would not seem to other than botanists 

 and agriculturists to be anything specially noteworthy. 

 But in the British Empire, where plant economics is 

 certainly better understood and its lessons more eagerly 

 and thoroughly applied than in any other community, it 

 is both true and surprising that no guide to the study of 

 plant diseases and their prevention — at least none worthy 

 of the name — has until now appeared. Nothing more 

 admirable than the papers on vegetable pathology con- 

 tributed by the Rev. Mr. Berkeley to the pages of the 

 Gardeners' Chronicle, and the many writings of this and 

 other authors scattered throughout our serial scientific 

 literature, can, within their range and for their time, be 

 shown elsewhere. But of recent years remarkable ad- 

 vances have been made, especially in Germany, in the 

 study of the aetiology of plant diseases, and an excellent 

 and comprehensive handbook was prepared a few years 

 ago by Prof. Frank. Without doubt this author has gone 

 as far as the state of science permitted him, but neverthe- 

 less a serious attempt to deal with vegetable pathology 

 has yet to be made, and the attempt must be preceded by 

 a great amount of laborious research. The activity shown 

 in the investigation of parasitic diseases leaves little to be 

 desired, but the many other ailments that the plant is 

 subject to are but little regarded. That injuries are done 

 by defective nutrition, by frost, and such like causes, is 

 doubtless well recognised, but beyond this recognition 

 there has not been very much inquiry into the matter. It 

 is as if we were to be content with classifying the diseases 

 of man into those due to the prevalence of east winds and 

 the like. 



While pathology is in this condition our therapeutical 

 resources must continue scanty. Much may be hoped 

 however from such researches in plant nutrition as those 

 of Dr. Gilbert and Sir John Lawes. The means in our 

 power of coping with the attacks of insects and of fungi 

 are, it must be confessed, not very effective. There is 

 doubtless something exhilarating in the wholesale destruc- 

 tion of insect pests by means of a judicious mixture of soap- 

 suds and petroleum (applied on occasion by a fire-engine), 

 and the heroic slaughter of the enemy may spur on the 

 administrator to further and greater deeds, but except for 

 very " local application " even this method will hardly lead 

 to generally useful results. More — much more — is to be 

 hoped from the encouragement of insectivorous birds, as 

 recommended by entomologists. In fungal diseases our 

 chief hope lies in " stamping out " either by means of the 

 interception of a generation (where possible) on a com- 

 paratively worthless host, or by rigorous destruction of 

 infected crops. It is true cases occur where timely ampu- 

 tation may save the remainder, and a method of cultiva- 

 tion (of potatoes) is under trial, the aim of which is to 

 check the disease in each case at a certain stage of its 

 Vol. xxx.— No. 782 



progress — but the result will be seen. The introduction 

 of new and "disease-resisting" races opens up also a 

 means of evading fungal diseases. 



Mr. Worthington Smith in the introductory chapter of 

 his book laments that " there are no special teachers of 

 vegetable pathology in this country, and the few men who 

 have made the subject more or less a specialty, have not 

 the time or opportunity for extensive or continued ex- 

 periment and research." As one of those who have given 

 much time and attention to this subject, Mr. Smith has 

 here endeavoured to make up in some measure for this 

 want by supplying us with a treatise on the diseases of 

 crops, selecting such as are of the first economic im- 

 portance, describing their phenomena in simple language, 

 and considering the best means of preventing attack. 

 With the exception of the attacks of Nematodes, he has 

 confined himself to vegetable parasites, and of these he 

 has supplied copious illustrations faithfully recording his 

 views of the structure and the phases passed through by 

 such organisms. The advice given throughout is cautious 

 and to the point ; the book is in very handy form, and 

 within the reach of all in point of price. As such, then, it 

 must be considered a decided gain to the farmer, the 

 gardener, and the author's fellow- workers. Many of the 

 last-named will regard with regret the fact that the 

 author has not seen his way to accepting the proofs of so 

 well-established a fact as the hetercecism of the Uredinece. 

 Mr. Smith devotes a chapter to the consideration 

 of the subject, in which he attempts to combat the 

 irrefragable evidence of the truth of this fact fur- 

 nished us by experiment. Such objections, to give but 

 one example, as that to the different periods occupied by 

 the cultivation-experiments of different observers are not 

 only of no account, but Mr. Smith must surely know 

 from his own experience that the germination and further 

 growth of spores as well as seeds vary exceedingly in 

 different circumstances even under the same observer's 

 hands. But it would be beyond the scope of this review 

 were I to enter upon any defence of the existence of 

 hetercecism in the Uredineas. What is more particularly 

 to be noticed in this section of the book is a theory of 

 the hereditary nature of parasitic diseases. At p. 197 

 the author says : — 



" We have shown that plants invaded by Puccinia and 

 AZcidium cany an hereditary disease by which they are 

 saturated, and that the disease is capable of reaching the 

 seeds and reappearing in the youngest seedlings. Now, 

 if plants thus suffering from hereditary disease, and 

 having the latent germs of disease in every part of their 

 organisation, are experimented upon in an unnatural way, 

 have spores of fungi placed near their organs of transpira- 

 tion, whose germ-threads can pierce the epidermis or 

 enter and choke the stomata and so reach their intercellu- 

 lar spaces, is it not likely that this inoculating process 

 may start into activity the latent germs of disease ? " 



This is illustrated by the "instance of a person consti- 

 tutionally subject to phthisis (consumption) : give that 

 person a cold and phthisis appears ; but the same cold 

 will give rise to rheumatic fever with a second constitu- 

 tion, and scrofula with a third, according to the tendency 

 of the individuals to these disorders." Since Mr. Smith 

 considers the hetercecism of the Uredinece as not proven 

 in spite of the nature and the amount of the evidence, 

 one cannot help being profoundly astonished at the ease 



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