May 31, 1888] 



NATURE 



in 



surface. Although this is not an absolute safeguard 

 against the attacks of fungi — simply because the germinal 

 tubes from spores can find their way through small cracks 

 at the margin of the wound, &c. — still it reduces the danger 

 to a minimum, and it is certain that valuable old trees 

 have been preserved in this way. 



Before passing to treat of the chief diseases known to 

 start from such wounds as the above, it should be re- 

 marked that it is not inevitable that the exposed surface 

 becomes attacked by fungi capable of entering the timber. 

 It happens not unfrequently that a good closure is effected 

 over the cut base of a small branch in a few years, and that 

 the timber of the base is sound everywhere but at the 

 surface : this happy result may sometimes be attained in 

 pines and other Conifers, for instance, by the exudation of 

 resin or its infiltration into the wood ; but in rarer cases 

 it occurs even in non-resinous trees, and recent investiga- 

 tions go to show that the wood formed in these healing 

 processes possesses the properties of true heart-wood. 

 At the same time there is always danger, as stated, and 

 we will now proceed to give a brief account of the chief 

 classes of diseases to which such wounds render the tree 

 liable. 



The first and most common action is the decay which 

 sets in on the exposure of the wood surface to the 

 alternate wetting and drying in contact with the atmo- 

 sphere : it is known that wood oxidizes under such 

 circumstances, and we may be sure that wounds are no 

 exception to this rule. The surface of the wood gradually 

 turns brown, and the structure of the timber is destroyed 

 as the process extends. 



The difficulty always arises in Nature, however, that 

 mould-fungi and bacteria of various kinds soon co- 

 operate in ani hurry these processes, and it is impossible 

 to say how much of the decay is due to merely physical 

 and chemical actions, and how much to the fermentative 

 accion of these organisms. We ought not to shut our 

 eyes to this rich field for investigation, although for the 

 present purpose it suffices to recognize that the combined 

 action of the wet, the oxygen of the air, and the ferment- 

 ing action of the moulds and bacteria, &c, soon converts 

 the outer parts of the wood into a mixture of acid 

 substances resembling the humus of black leaf-mould. 



Now as the rain soaks into this, it dissolves and carries 

 down into the wood below certain bodies which are 

 poisonous in their action on the living parts of the 

 timber, and a great deal of damage may be caused by 

 this means alone. But this is not all : as soon as the 

 decaying surface of the wound provides these mixtures of 

 decomposed organic matter, it becomes a suitable soil for 

 the development of fungi which are not parasitic — i.e. 

 which cannot live on and in the normal and living parts of 

 the tree — but which can and do thrive on partially decom- 

 posed wood. The spores of such fungi are particularly 

 abundant, and most of the holes found in trees are due to 

 their action. They follow up the poisonous action of the 

 juices referred to above, living on the dead tissues ; and 

 it will be intelligible that the drainage from their action 

 aids the poisonous action as it soaks into the trunk. It 

 is quite a common event to see a short stump, projecting 

 from the trunk of a beech, for instance, the edges of the 

 stump neatly rounded over by the action of a callus 

 which was unable to close up in the middle, and to find 

 that the hollow extends from the stump into the heart of 

 the trunk for several feet or even yards. The hollow is 

 lined by the decayed humus-like remains of the timber, 

 caused by the action of such saprophytes as I have re- 

 ferred to. Similar phenomena occur in wounded or 

 broken roots, and need not be described at length after 

 what has been stated. 



But, in addition to such decay as this, it is found that if 

 the spores of true wound-parasites alight on the damp 

 surface of the cut or broken branch, their mycelium can 

 extend comparatively rapidly into the still healthy and 



living tissues, bringing about the destructive influences 

 described in Articles III. and IV., and then it matters 

 not whether the wound closes over quickly or slowly — the 

 tree is doomed. H. Marshall Ward. 



( To be continued?) 



HERVE MANGON. 



T N the current number of La Nature there is an 

 •*• interesting article, by M. Gaston Tissandier, on 

 Charles Francois Herve^ Mangon, whose death we 

 announced last week. The following are the essential 

 facts noted by M. Tissandier. 



Hervd Mangon was born in Paris on July 31, 1821, and 

 was trained by his father, a military surgeon, who devoted 

 himself almost entirely to the education of his t son. 

 At the age of nineteen the young man entered 1'Ecole 

 Polytechnique, and two years later 1'Ecole des Ponts et 

 Chaussdes. He afterwards acted as engineer for several 

 railways, but his chief interest at that time was in science 

 as applied to agriculture. 



In 1850 he published his "Etudes sur les Irrigations 

 de la Campine Beige," and on the " Travaux Analogues 

 de la Sologne." This work attracted great attention, 

 and brought about important improvements in the 

 French laws relating to agriculture. Drainage was then 

 scarcely known, even by name, in France. In 1851, M. 

 Hervd Mangon published a work on the subject, which 

 was considered so valuable that he received from the 

 Academy of Sciences the decennial prize for the most 

 useful work on agriculture issued during the previous ten 

 years. His practical instructions on drainage, of a little 

 later date, were widely circulated, and it is estimated 

 that the results of his researches have led to an increase, 

 in the French revenue, of fourteen millions of francs 

 yearly. Irrigation, manures, chemical refuse, and every- 

 thing by which land might be fertilized, were made by 

 him subjects of prolonged and careful study. He visited 

 the principal agricultural works and irrigations in France, 

 Belgium, Scotland, Spain, and Algiers, and summed 

 the knowledge thus acquired in his " Traite de Ge"nie 

 Rural." 



These researches were followed by meteorological 

 studies, in which he took the deepest, interest. He in- 

 vented or improved many meteorological instruments, 

 and on his estate at Bre'court in Normandy he organized 

 a model meteorological station, provided with the latest 

 scientific improvements. Towards the end of his career 

 he played a most important part in the reorganization of 

 the French meteorological service, and he became the 

 President of the Meteorological Council. He contributed 

 also to the organization of the scientific mission to Cape 

 Horn, and to many other enterprises useful to science. 



As a Professor, he created at the Ecole des Ponts et 

 Chausse'es the course on " Hydraulique Agricole " 

 (1849) > at tne Conservatoire des Arts et Me'tiers the 

 course on " Travaux Agricoles et de Ge'nie Rural" (1864) ; 

 and at the new Institut National the course on " Genie 

 Rural" (1876), a science of which he may be considered 

 one of the founders. He lectured with ease, and his 

 expositions were always clear and methodical. 



He possessed an extraordinary power of work. He 

 rose early, carried on his own correspondence, and did 

 all his literary work without assistance. His personal 

 tastes were simple, and the activity of his body seemed to 

 keep pace with that of his mind. He welcomed fellow- 

 workers cordially, and readily offered them counsel and 

 help, his disposition being one of rare generosity. He 

 was skilful in working in wood and metal, and always kept 

 in his library a quantity of apparatus made by himself. 

 With this he was constantly experimenting, sometimes 

 even getting up during the night to carry on some 

 research of special interest. _ 



