364 BOOKS AND CURRENT LITERATURE 



uration, dormancy, and germination) may exert a predetermining influ- 

 ence upon the whole subsequent course of growth and development. 

 It is obvious from the point of view of crop production that this ques- 

 tion as to the equality and size of the plants produced from any sample 

 of seed may be even more important than the question as to what 

 percentage of the seed is capable of germination." 



The problem as outlined and discussed here is seen to be one of 

 great scientific and economic importance. 



Soaking seeds in water for periods varying from 6 to 24 hours was 

 shown to have profoundly harmful effects upon the subsequent growth 

 of certain plants. Differences existed which would often vitiate the 

 results of an experiment. 



The effect of parental conditions, of harvesting conditions, and of 

 conditions during the germination and seedling stages of the plant are 

 critically discussed. The importance of the "compound interest" 

 law as a means of expressing the growth of a plant is pointed out. It 

 appears that there are two main factors determining the final yield 

 (a) the initial " capital," and (b) the "rate of interest." The first 

 of these is a great predetermining factor and is not modified by sub- 

 sequent environmental conditions, but the other factor may be some- 

 what affected by such conditions. 



The selection of vigorous seedlings is matter of common practice 

 yet little is known whether the vigor of the seedling is correlated with 

 a vigorous adult. "The critical question is therefore — Can we pro- 

 pound a law to the effect that increased vigor of seedling development 

 due to environmental conditions as distinct from hereditary causes, is 

 correlated with increased vigor of growth throughout the life of the 

 plant and with increased yield independently of the subsequent environ- 

 mental conditions? 



These and other questions are discussed in a spirit which cannot 

 fail to be stimulating to all further work in this important field. — 

 H. S. Reed. 



The Cycads. — Recently another addition has been made to the 

 University of Chicago Science Series under the title The Living Cycads. 1 

 The text is divided into three parts. Part I gives the distribution of 

 the living cycads, and is made very interesting reading by the inclu- 



1 Chamberlain, Charles J. The Living Cycads. University of Chicago Press. 

 1919 ($1.50). 



