150 JOURNAL OF THE EOYAL HORTICULTURAL SOCIETY. 



creed. It is, however, really an exceedingly clear proof of the inheritance 

 of acquired characters. 



The following quotation is worth giving in extenso : 



" Whether the lowland and highland firs are to be considered (with 

 Cieslar) as physiological varieties or whether one ought to speak of 

 climatic forms (Schroter) I will not decide. The expressions Species, 

 Variety, Race, have been manufactured by man in order that he may be the 

 better, able to find his way in the endless variety of organic nature. 



" As a matter of fact there are neither Species nor Varieties, but only 

 individuals. The better we learn to know Nature, the more difficult it 

 becomes strictly to define such terms, and so the greater becomes the 

 general confusion." 



It is, of course, uncertain whether such differences would persist 

 during the whole life of the tree, but the u mountain characters " have 

 been preserved for the first seven years of the life of the trees. Nobody 

 at present living can justifiably expect to be living sixty-three years hence, 

 when the question may be decided by the examination of trees seventy 

 years old. In the meantime it certainly seems the safest plan to suppose 

 that these inherited characters will not be lost. 



It is shown in Friih and Schroter' s classical work on the Moors of 

 Switzerland that the Picea excelsa was amongst the first trees (with 

 Birch and Alder) to enter that country after the retreat of the glaciers at 

 the end of the Great Ice Age. The temperature at that time may have 

 been very similar to that now existing in the mountains. Thus Professor 

 Engler holds that these high-altitude firs had at that time their slow 

 growth and other characters adapted to low temperatures, and that the 

 lowland Picea excelsa acquired their present characteristics at a much 

 later period. This would be in the time of the Helvetii and in the earlier 

 part of the Middle Ages, when the woods of Silver Fir and deciduous trees 

 had been cleared away. In the times of the Swiss lake villages Picea 

 excelsa seems not to have existed in the low grounds. So that the 

 adaptation of the lowland Picea excelsa to its present place has not 

 required a very long period. 



It is very unfortunate that there is no possibility of publishing in 

 English, and in extenso, such papers as this of Professor Engler, but 

 what has been said gives some idea of the scope and importance of his 

 researches. 



