CHAPTER XXXV 



DISEASES 



LIKE other living organisms, plants and trees are liable 

 to the attacks of diseases. When carefully examined, 

 these diseases are found to be not altogether dissimilar to those 

 by which the animal kingdom is affected. Animals suffer from 

 lung diseases, and the breathing of plants may also suffer and 

 be seriously affected by unsuitable conditions. Canker attacks 

 trees as well as animals. Unhealthy growths afflict many 

 animals, and plants suffer in the same way. The blood of 

 animals and the sap of trees can both become poor and anaemic. 

 Fungi and bacteria are the sources of many diseases in both the 

 animal and vegetable kingdom which are constantly being 

 investigated by new methods in science. Trees, like animals, 

 are subject to such accidents as broken limbs. Poisons have 

 evil effects on all kinds of animals and all forms of vegetable 

 life. When one comes to regard trees as living beings with an 

 intelligence all their own, then one can better comprehend the 

 nature of the diseases from which they suffer and how they 

 combat them. 



The chief sources of infectious disease from which trees suffer 

 are the fungi and bacteria. While the ordinary members of the 

 vegetable kingdom generally derive from air and water and soil 

 the nourishment necessary for life and growth, the fungi, which 

 occupy so considerable a place in the vegetable world, feed, like 

 animals, on already-formed organic substances. Injured or 

 unhealthy trees are always most readily attacked. 



Professor Erikson, a Swedish botanist, has devoted long 

 study to fungoid diseases and gives it as his established convic- 

 tion that year by year the diseases of cultivated plants become 

 more numerous and disastrous. It is stated that parasitic fungi, 

 which hitherto have proved almost harmless, have changed 

 their nature and become most destructive. It is true that much 



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