2i8 Forestry Quarterly. 



conclusion diametrically different from that made by Mayr, 

 namely, that for planting native or naturalized species the seed 

 must be collected in the region in which they are to be planted or 

 at least from localities which climatically are very similar to 

 those in which they are to be planted. Mayr, on the other hand, 

 without really disproving Vilmorin's, Engler's, and Cieslar's ex- 

 periments, cites his own experiments which tend to show that 

 only typical characteristics are transmitted and not deviations 

 from the type due to changed climatic conditions. This diver- 

 gence of opinion as to what characteristics are transmitted 

 through inheritance shows that the question does not allow of 

 general sweeping conclusions. 



Engler further points out that the acquisition by forest trees 

 of new characteristics and their transmission to future genera- 

 tions does not require such an infinitely long time as is claimed by 

 Mayr. He mentions interesting facts with regard to the spruce. 

 After the retreat of the glacier into the mountains, spruce was 

 one of the first species which reappeared in the Swiss valley, the 

 climate of which at that time resembled closely the climate of the 

 higher altitudes. Later, when the climate of the valley became 

 warmer and the conditions became favorable for the growth of 

 hardwoods, the latter crowded out the spruce into the moun- 

 tains. In the historic epoch, when the forests in the valleys were 

 badly cut and abused, spruce descended again from the moun- 

 tains into the valley. With the aid of material which was found 

 in excavations, it was possible to determine that spruce was not 

 present in the valley in the neolithic time, and that it appeared 

 only in the helvetic period, that is, early in the middle ages. This, 

 according to Engler shows that it did not take such a long time 

 for the spruce to acquire biological characteristics which enabled 

 it to grow in the valley. 



The climatic factor is laid also at the foundation of all cultural 

 operations in the forest — thinnings, planting, etc. This, how- 

 ever, would take us into the other parts of Dr. Mayr's most in- 

 teresting book, the review of which must be left for some other 



