Preceeded by years of normal precipitation and with no excessive 

 stunmer heat. The seed year was not very heavy and prohahly not very general 

 as only a few seedlings of this age were found. If this year was not a 

 general seed year, we should expect a seed year in 1911 since 1909 was 

 very dry.lTo such seed year is indicated by the reproduction, the next year 

 comming in 1914. Since 1912 was someTvhat below the normal and was preceeded 

 by a ntimber of dry years, this seed year fits in with our;:^theory exactly. 

 The summer of 1915 has been very wet and rather cool, and following out 

 our theory we should expect no seed year until 1918, and unless next summer 

 is dry, not until 1919 or 1920. 



There is not enough data at hand to warrant the unconditional 

 endorsement of this theory, but there certainly seems to be some relation 

 between precipitation, or rather available soil water, and the production 

 of seed, and the periodicity of seed years. 



In the Uentralblatt fur das gesamte i!'orstwesen,for June, 1906. 

 there appeared a short article under "Uoti)(zen"entitled Die Ursachen der 

 Jrilutenbildung.A rather free translation of this article appeared in the 

 i'orestry Quarterly, vol. 4, page 205 and was as follows :- 



n'i'he celebrated plant physiologist , J. Sachs, maintained that 

 flowering was dependent upon the presence of certain materials, produced 

 at certain periods and acting as stimuli. In the laturwiesenschaftliche 

 ■.Tochenschrift (1905,p 573) the primary cause is sought in certain weather 

 conditions which produce these majrerials and act upon them. That light 

 is an essential factor in forming flower materials may be proved by 

 placing plants in a dark room, when no flowers will be produced; similarly, 

 shrubs shaded on one side and exposed on the other to full sunlight 

 flower mainly on the latter side.jjiio^^yer materials may, however , be deposited 

 as reserve material in bulbs, which may then develop flowers in the dark. 

 Temperatures also influence flowering favorably, but in the tropics 

 excessive hiimidity may counteract favorable temperature influence, so 



