2'8o 



SCIENCE-GOSSIP. 



Text-Book of the Diseases of Trees. By Professor 

 R. Hartig, of the University of Munich. Trans- 

 lated by William Somerville, D.GEc, B.Sc, 

 F.R.S.E., F.L.S. Revised and edited, with a 

 Preface, by H. Marshall Ward, B.Sc, F.R.S,, 

 F.L.S. , F.R.H.S. Pp. xvi. and 331, with 159 

 Illustrations. (London: Macmillan and Co., 1894.) 

 Price 10s. net. 



The pathology of plants has only within com- 

 paratively recent times received systematic atten- 

 tion from properly 

 trained scientific in- 

 vestigators. That 

 the subject is one of 

 inestimable value to 

 mankind, from an 

 economic point of 

 view, there cannot 

 be any doubt, apart 

 from its great interest 

 to its students. The 

 important contribu- 

 tion now before us 

 will do much to 

 encourage others to 

 work in the same 

 field of knowledge. 

 The thanks to all 

 connected with the 

 introduction to an 

 English audience of 

 Professor Hartig' s 

 well-known labours 

 are due from the 

 many who have now 

 an opportunity of 

 obtaining a guide to 

 a better knowledge 

 of the diseases of 

 forest trees. It must 

 not be imagined, 

 however, that there 

 is nothing more to 

 learn about the sub- 

 ject, which is, in 



fact, only in its embryonic stage, though rapidly 

 maturing. Indeed, there are laurels in plenty 

 to be won by the accurate and conscientious 

 investigator. As a type of that kind of student, 

 Professor Hartig himself stands pre-eminent, as 

 pointed out by Professor Marshall Ward in his 

 preface to this work. He instances Hartig's 

 admirable discussion of the complex phenomenon 

 of " Leaf-Casting," on pages 110-117, as a model of 

 thoughtfulness and scientific accuracy and acumen, 

 to which all workers in this branch of botany must 

 look up. 



_ An important feature of this edition is the adapta- 

 tion of the instances and examples of the diseases 

 treated to our native flora, instead of literally 

 following the text of the original, which was 

 designed for German readers, with local examples, 

 some of which do not occur in these islands. In 



Pine Shoot Twist Disease. 

 (From " Text-Book of the Diseases of Trees.") 



this selection, Professor Marshall Ward, as editor, 

 has been as judicious as in the rest of his control 

 of the text, by giving Hartig the full benefit of his 

 experience, without overshadowing in the least the 

 original author. 



The introduction to this work is important and 

 interesting. Like the rest of the book it is thought- 

 fully prepared, and practically sums up the present 

 knowledge of the diseases of plants, after giving a 

 short history of the development of the science. 

 From this chapter, as from the whole work, much 

 may be learned by the ordinary reader without 

 requiring any special knowledge. In treating the 

 subject, Professor Hartig summarises the diseases 

 into five classes, according to the external influences 

 which induce them, which are : (1) Those induced 

 by phanerograms, (2) those induced by cryptogams, 

 (3) wounds, (4) unfavourable conditions of the 

 soil, and (5) unfavourable atmospheric conditions. 

 Remarking upon the second factor in this list, he 

 says : ' ' There are a great number of fungi which 



can only attack a 

 certain species of 

 tree when plants of 

 another species occur 

 in the vicinity on 

 which the particular 

 fungus, at certain 

 seasons of the year, 

 may complete its de- 

 velopment. Locali- 

 ties in which many 

 aspens grow impart 

 to the pines a pre- 

 disposition for the 

 disease known as 

 pine-twist (caused by 

 Melamfsora Tvemulce. 

 pinitorquum) . Rho- 

 dodendrons abound- 

 ing in a district make 

 the spruces liable to 

 'leaf-blister' (caused 

 by Chrysomyxa rho- 

 dodendri) . The mere 

 existence of unin- 

 terrupted woods, 

 composed of a single 

 species of tree, may 

 give rise to dangers 

 leading to extensive 

 epidemics. Pine 



larch woods away 

 from mountainous 

 regions almost 

 always succumb to 

 canker, whereas larches mixed with other trees 

 may remain unaffected." With regard to the 

 susceptibility of trees to a certain class of diseases 

 through wounds, the author says: "When a tree 

 is pruned it thereby incurs an abnormal predis- 

 position for a series of wound diseases, infectious 

 or otherwise, which can be got rid of by the 

 application of timely and appropriate — that is to 

 say, antiseptic dressings. A hailstone strikes the 

 cortex of a tree and injures it. This creates an 

 abnormal condition, which may lead to an in- 

 fectious disease should certain fungi settle on the 

 cortex." 



We strongly recommend this work to our more 

 thoughtful readers, and especially as one suitable 

 for the many public libraries now arising around us. 

 We have to thank the publishers for the use of the 

 accompanying illustrations. J.T.C. 



