250 CRYPTOGAMIC PLANTS INJURIOUS TO FOREST TREES. 



XXIX. Cryptogamic Plants Injurious to Forest Trees, and their 

 Treatment* By Malcolm Dunn, the Palace Gardens, Dal- 

 keith Park, Edinburghshire. 



The subject which I have to bring under the notice of the meet- 

 ing is of such a comprehensive nature, and has so many minute 

 but important ramifications, that, to do it anything like justice, 

 we would require a whole day for its discussion instead of the very 

 limited time at our disposal ; and even then we could only notice 

 in detail some of its more prominent and characteristic features. 

 The class Cryptogamia forms a very numerous section of the vege- 

 table kingdom, and includes all those genera the flowers of which 

 are either absent or formed on a plan different from that of ordi- 

 nary flowering or phamogamic plants, and the reproductive organs 

 of which are not true seeds, containing an embryo, but mere cells 

 enclosing a granular matter, which, by germination, produces a 

 thread, or mass of threads, a cellular body, a membrane, etc., as 

 the case may be, which either at once gives rise to the fruit or to 

 a plant producing fruit ; but to enter upon a botanical definition 

 of all the differences and distinctive featm*es of the various orders 

 and genera into which the class Cryptogamia is divided, is not 

 necessary for the elucidation of the object we have in view, and, 

 in fact, can only be followed out in a satisfactory manner by 

 those who have an intimate knowledge of plant life in all its 

 varied phases, and of the structure and functions of all parts of 

 plants throughout the vegetable kingdom. 



Plants, like animals, are subject to numerous diseases, both 

 functional and organic, and they arise from various causes, some 

 being constitutional and hereditary, but frequently, on the other 

 hand, many of them are induced by bad food, imperfect nutriment, 

 a vitiated atmosphere, want of light, the attacks of cryptogams, 

 and other causes, for which in many cases effective remedies are 

 known, and in all of which some likely remedy can be suggested. 

 The study of the diseases of trees is essential to their good cultiva- 

 tion, for although in many instances perhaps but little can be done 

 toward arresting disease in any individual tree, much may be done 

 by proved experience and the judicious use of rational means in 

 preventing the spread of those which are infectious or contagious, 

 * Read at the Animal General Meeting, 6th November 1877. 



