532 BOTANICAL GAZETTE [june 



the community. On the other hand, owing to the complex nature of the mental 

 traits of the highest type, the brightest examples of inherent ability have come 

 and will come from chance mating in the general population, the common 

 people so-called, because of the variability there existent. There can be no 

 permanent aristocracy of brains, because families, no matter how inbred, will 

 remain variable while in existence and will persist but a comparatively short 

 time as close-bred strains. But he is a trifler w r ith little thought of his duty to 

 the state or to himself, who, having ability as a personal endowment, does not 

 scan with care the genealogical record of the family into which he enters. " 

 "The hybridization of extremes is undesirable because of the improbability 

 of regaining the merits of the originals, yet hybridization of somewhat nearly 

 related races is almost prerequisite to rapid progress, for from such hybridiza- 

 tion comes that moderate amount of variability which presents the possibility 



of the superindividual, the genius Further, there must be periods of 



more or less inbreeding following racial mixtures, if there is to be any high 

 probability of isolating desirable extremes. A third essential in the produc- 

 tion of racial stamina is that the ingredients in the melting pot be sound at 

 the beginning, for one does not improve the amalgam by putting in dross." 

 One of the most valuable features of the book is the admirable bibliog- 

 raphy of 225 titles. — M. C. Coulter. 



NOTES FOR STUDENTS 



Temperature and the cobalt chloride method of measuring transpiration, — 



In the improvement by Livingston and Shreve* of Stahl's cobalt method of 

 measuring transpiration, one question has remained unanswered, namely, Is 

 it sufficiently accurate to regard the temperature of the slip as it lies on the 

 leaf as being the same as that of th$ surrounding air ? Shreve 6 has answered 

 this question by making use of a thermo-electrical method for measuring leaf 

 temperatures. This method differs from previous ones in the avoidance of 

 the wounding of the leaf and the resulting temperature complications. Using 

 this method, Shreve has demonstrated that both in the determination of the 

 index of transpiring power by cobalt slips, and in the standardizing of the 

 slips themselves over a porous evaporating surface, no error results from 

 using the temperature of the air surrounding the apparatus instead of the 

 temperature of the slips themselves. — S. V. Eaton. 



s Livingston, B. E., The resi 

 loss. Plant World 16:1-35. 1913. 



Shreve 



19:287-309. 1916. 



paper, 



Plant World 



thermo-electrical method for the determination 



perature. Plant World 22:100-104. figs. 2. 1919. 



, The role of temperature in the determination of transpiring 



paper. Plant World 22:172-180.^.1. 1919. 



