172 Studies in Forestry [CHAP. VIIT. 



This seems a not unsuitable opportunity of noting one 

 great difference between human beings and trees of the forest, 

 and of pointing out that there is no such thing as hereditary 

 disease in tree-growth. Thus Professor Hartig says l : 



* The hereditary transference of diseases to sup ceeding generations is 

 unknown in the vegetable world. The seed of plants inflicted with all 

 possible sorts of diseases may be utilized, without the slightest concern, 

 for the formation of new crops.' 



Where woodland crops are to be formed for the first time, 

 a choice exists only between sowing and planting, in connex- 

 ion with which leaving out of sight the special requirements 

 of the various genera and individual species of forest trees 

 certain general considerations require to be weighed. 



With regard to the soil, experience has shown that, on 

 places unfavourable to the early development of young crops, 

 planting is preferable to sowing, owing to the greater sensitive- 

 ness and need of protection of young seedlings during the 

 first stages of their existence. And better results are usually 

 obtainable from planting than from sowing, both on very 

 damp, wet, cold, or stiff soils with a tendency to being lifted 

 by frost, and on very loose soils apt to dry up easily, or such 

 as may have become deteriorated superficially through insola- 

 tion and exposure to exhausting winds, or which are liable to 

 inundation, &c. Where, owing to rank herbage of grass and 

 weeds, young growth has to struggle for its very existence, 

 sowing is the exception, and planting the rule, more especially 

 when the genera of trees forming the young crop are of slow 

 initial development. Unfavourable situation with regard to 

 climate, by retarding the growth during the first few years, 

 also weights the balance in favour of planting, especially in 

 raw, damp localities exposed to frost. Where planting up is 

 to take place on tracts that have been drained, but which 

 are still damp enough to show a strong growth of rank weeds, 

 sturdy transplants of hardy species, little sensitive to frost 

 1 Lehrbuch der Baumkrankheiten, 2nd edit. 1889, p. 16. 



