362 BOOKS AND CURRENT LITERATURE 



or variation, as is the fact, and as such it has much interest, but the 

 feature of the work to which the reviewer wishes to direct attention is 

 that correctly connoted by the title, that is, to the influence of the tem- 

 perature of the soil itself on the behavior of the plants without regard 

 to the strains of corn employed. 



In judging the influence of warm and cool soils on seedling corn the 

 following points were considered: viability, length of mesocotyl, emer- 

 gence, length of plant, weight of seedlings, vigor of seedlings, and vari- 

 ability in lengih of seedlings. Am.ong the leading results and conclu- 

 sions the following can be noted: The sum.mer-grown seedlings were 

 32.93% m.ore viable than those that were grown in autumn. The meso- 

 cotyl was 10.9% longer in the seedlings grown in summer than in those 

 grown in autumn. In summer the corn seedlings "came up" somewhat 

 over 10 days sooner than in autumn, and the average emergence for 

 the two seasons was 4.06 and 14.63 days, respectively. The length of 

 the plants grown in sum.m.er was found to average 41.6 m.m. wliile the 

 length of plants grown in autumn was 11.7 mm. The average weight 

 of the summer-groAvn seedlings was 4.27 grams while the average 

 weight of the seedlings grown in autumn was 1.27 grams. As to the 

 vigor of the seedlings, that is, "the weight of the crops less the seeds 

 planted," it was found that the seedlings raised in summer averaged 

 n'earty four times as heavy as those grown in autumn. Thus in many 

 respects the seedlings grown in summer are immensely more vigorous 

 than those grown in autumn, but as regards variability, the autumn- 

 grown seedlings ranked first. The variability in length of seedlings 

 of summer was 1.08 per cent, while those that were grown in autumn 

 had a variability in length of 2.32%. 



Although it is thus shown that the shoots of the corn seedlings vary 

 in development directly with the temperature of the soil, it would be 

 of considerable interest to know whether the development of the roots 

 of the two corn croi:js varied also and to what degree. That this would 

 be the case would be expected, however, from the experience of other 

 writers with other species. Indeed, it might even be not too much to 

 suggest that a close study of root behavior under such conditions as 

 those which obtained in the study in question, may have given results 

 quite as applicable to the case, from, the present point of view at any 

 rate, as the study of the shoots only. 



The work of Halsted and Waksman recalled to th<^ reviewer a series 

 of analogous experiments which he carried out on cuttings of Opuntia 

 versicolor at the Coastal Laboratory, in which the soil only was heated, 



