Books and Current Literature. 



241 



Just why the cones of the silica-form open early, while 

 those of the lime-form remain closed, can not be readily ex 

 plained. A thorough drying of the cones of both forms causes 

 them to open, and we would quite naturally presume that the 

 difference is more or less closely related to the soil moisture 

 conditions. On the siliceous soil with its poor water content, 

 there is less moisture available to be supplied to the cones, and 

 they open therefore, as soon as mature. 5 A he fine, compact, 

 lime soil, on the other hand, has a better water content so that 

 more water may be supplied to the cones, and these remain 

 closed in consequence. This explanation, however, does not 

 prove satisfactory In the lime-form, as long as the stem of the 

 cone remains united to the parent wood, moisture can be sup- 

 plied to them, but when, as often happens, the stem of the cone 

 becomes separated from the parent wood as a result of the growth 

 in diameter, no moisture can be supplied directly to the cones. 

 The latter condition is of very common occurrence, and yet cones 

 do not open which have had no direct connection with the woody 

 tissues for twenty-five or thirty years. 



In the dissemination of the seed, the factors of chief im- 

 portance are wind and fire. With the silica-form, where the 

 cones open shortly after maturity, the first named factor is 

 primarily important because of the relation it bears to seed dis- 

 persal, fire being a secondary consideration. In the lime-form 

 the conditions are reversed, fire being of primary importance, 

 and the wind a factor w r hich may have only a secondary influence 

 or even none at all. 



An interesting article appears in a German annual report 

 (Jahr. d. Verein. f. ang. Bot., p. 182, 1907.) w r hich is very im- 

 portant if substantiated by further observation. Count von 

 Armin-Schlagenthin, who is connected with a German-Swedish 

 seed establishment, and which acts as an increase agent of cer- 

 tain German pedigreed seeds, reports that the climatic condi- 

 tions of tw r o winters produced remarkable results upon the pedi- 

 greed wheats. These results were nothing else than very radical 

 mutants which appeared in the harvest following the freeze. 

 One of the most remarkable things is that the mutants were 

 formed after the germination of the seed, a kind of mutant 



