i96 ^HE iPLANT World. 



between the rates of transpiration from differently shaped 

 leaves; it is to be related to the effect of the vapor blanket, the 

 margins of a surface being much more efficient in evaporation 

 than the central portion. 



It is clear from Renner's admirable analytical studies 

 that the underlying physical principles of plant transpiration 

 (even when all intra-foliar changes such as stomatal movements 

 etc., are corrected for) are not simply those of gas difl'usion. 

 The phenomena are modified by size, shape and position of the 

 leaves, so that, as the author well points out, it is essential to 

 understand these physical modifications as far as possible, 

 so as to avoid confusion of these with supposed physiological 

 regulation. — Burton E. Livingston. 



Mendelism. — Punnett has published a new edition of this 

 excellently written treatise on ]\Iendelism,* which brings it up 

 to date and makes it, like the two preceding editions, the most 

 readible account of recent progress in working out the laws of 

 heredity. No attempt is made at exhaustiveness but each 

 phase of the subject is illustrated by typical cases chosen most- 

 ly from the experiments of Bateson and the author's other 

 associates at Cambridge, England. The checker board method 

 of solving Mendelian problems is presented ^^ith great simpli- 

 city and used with such frequency that the reader will gain 

 a clear conception of the method and its usefulness. In 

 one of these checkerboards (p. 52) three squares are blackened 

 which should be white, and three squares which contain C and 

 B and which should therefore be black are labeled "albino." 

 The author omits all discussion of the chromosomes on the 

 ground that there is not sufficient unanimity of opinion as to their 

 significance in relation to I\Iendelism to make a discussion of 

 them suitable for popular treatment. The reviewer considers 

 this omission unfortunate, and believes that a chapter on the 

 chromosomes presented with the same clarity that characterizes 

 the other chapters, would have added value to the book. The 

 introduction of many excellent figures and six plates, five of 



♦Punnett, R. C, Mendelism. ThirJ. edition tntirely rewritten and enlarged; pp. 

 14 192. Figs. 3'. Pis. 6 and frontispiece portrait. 1911. New York: Macmillan Co. $1.25 



