CURRENT LITERATURE 
BOOK REVIEWS 
Genetics 
Some one once said, perhaps more epigrammatically than truthfully, “the 
progress of a science is in direct proportion to the mathematics used in its 
development.” Whether generally true or not, the constant and rapid progress 
of genetics since the introduction of Mendel’s mathematical notation is a great 
argument in favor of the statement. At the same time, the chaos that can 
in mathematics were the first to forget that their science is merely a shorthand 
method of stating the facts, that no more can come out than goes into the 
mill, though it should come out in a shape more conducive to thorough mental 
digestion. The slogan of certain biometricians, “there are no premises, all is 
treatment,” has brought many biologists to that state of mind in which they 
could take seriously Por’s sly dig in the “Purloined Letter.” In speaking of 
the necessity of putting oneself in the mental attitude of the thief if the hiding 
Place of the stolen letter were to be discovered, he says: ‘‘As poet and mathe- 
matician, he (the thief) would reason well; as mere mathematician he could 
not have reasoned at all.” 
It remained for JoHANNSEN to prove that he is poet, biologist, and mathe- 
matician, by showing some four years ago the true relation of KARL PEARSON’S 
beautiful developments of mathematical methods to _ jriactis The 
motto through the whole 25 chapters of his 500-page book was: “Wir miissen 
die Erblichkeitslehre mit _— nicht aber als Mak treiben!”’ 
JOHANNSEN’s work on the comp e permanence of homozygous types pub- 
lished under the title Ueber eae ke in Populationen und in reinen Linien 
(1903) had already been enthusiastically received by many investigators, partly 
by reason of the author’s mastery of a persuasive style and partly because the 
conclusions fitted data with which his readers were personally familiar. For 
these reasons, this elaboration of his ideas met with a cordial reception that is 
not the fate of many textbooks. But one unfavorable criticism of any impor- 
ee could be made. The author did not treat adequately the numerous 
genetic researches in which the problems of heredity had been attacked by 
methods unlike his own. There is no hesitancy, therefore, in saying that the 
new edition, with its 30 chapters and 722 pages, to which this criticism may not 
: * JOHANNSEN, W., Elemente der exakten Erblichkeitslehre. Zweite Auflage. 
VO. pp. xi+723. figs. a5 Jena: Gustav Fischer. 1913. 
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