142 TRANSACTIONS OF ROVAL SCOTTISH ARBORICULTURAL SOCIETY. 



Of the conifers mentioned Abies pectinata and Pinus Peuke 

 cast their seed in autumn. During the winter it lies on the 

 ground partly covered with needles or leaves. It is exposed to 

 low temperatures (frost) and the soil moisture, or it may be 

 covered by snow. Respiration and transpiration are reduced 

 under these external factors. Methods of storage which 

 simulate the natural hibernation and expose the seed to 

 similar factors, like those in experiments 3a and 3/^, give the 

 best results, while a low moisture percentage and temperature 

 just above freezing-point give bad results. 



Picea excelsa, Pinus silvestris, and Larix europaea cast their 

 seed in late winter or spring. The factor which in the case of 

 Abies and Pinus Peuke gave the best results, namely soil moisture, 

 in this case gave the worst (Experiment No. 3a). Low tempera- 

 tures have a beneficial effect on the seed of the three species named, 

 but not in combination with soil moisture. On the other hand, 

 air moisture in combination with low temperature exerts a 

 greater or smaller beneficial influence on the preservation of the 

 germination percentage, although a room temperature in the 

 case of Pinus silvestris does not reduce the power of germination. 



Of broad-leaved trees only those which cast their seed in 

 autumn come under consideration. It should be noted that 



