SCIENCE 



Friday, July 17, 1914 



CONTENTS 



The Principles of the Theory of Mutation: 

 Pkofessoe Hugo de Veies 77 



The Prohlem of Lighting in its Belation to 



the Efficiency of the Eye: Dr. C. E. Feeree. 84 



Carl Fuchs: Feank E. Blaisdell, Se 91 



Estimates of Population 92 



Scientific Notes and News 94 



and Educational News 97 



Discussion and Correspondence : — 



Lightning Flashes: De. Cleveland Abbe. 

 A New Form of Collecting Pipette : Aethub 

 M. Banta. Is Melanism due to Food? Wm. 

 T. Cox 98 



Scientific Boohs: — 

 Iddi/ngs on Igneous Boclcs: Dr. Whitman 

 Cross. Allen's Commercial Organic Analy- 

 sis: Professor Lafayette B. Mendel. 

 Fantham and Porter on Minute Animal 

 Parasites: Propessoe Gaet N. Calkins. 100 



Special Articles: — ■ 



Direct Proof through Non-disjunction that 

 the Sex-linked Genes of Drosophila are 

 .Borne by the X-chromosome : Calvin B. 

 Bridges. Sot-water Treatment for Cotton 

 Anthracnose: H. W. Barre and W. B. 

 Aull 107 



The American Chemical Society. IV: De. 

 Charles L. Parsons 110 



MSS. intended for publication and books, etc., intended for 

 review should be sent to Professor J. McKeen Cattell, Garrison- 

 on-Hudson, N. Y. 



THE PBINCIPLES OF THE THEOBY OF 

 MUTATIOm 



Unity of internal structure combined 

 with a great diversity of external forms is 

 the great principle of organic differentia- 

 tion. Lamarck was the first to point this 

 out and to explain it by his theory of com- 

 mon descent. But the science of his time 

 did not afford a sufficient body of facts in 

 proof of his conception, and he failed to 

 convince his contemporaries.^ 



1 Address delivered at the University of Brussels, 

 January 17, 1914. 



2 "The Mutation Myth" is the title of a recent 

 article in this journal, N. 8., Vol. XXXIX., 

 No. 1005, April 3, 1914, p. 488. Its author, Ed- 

 ward C. Jeffrey, starts from the conception that 

 the mutation theory has been derived from 

 my experiments with Oenothera LamarcTciana 

 and allied species. This opinion is indeed, even 

 yet, not unfrequently held by those who have not 

 read my books. It is obviously erroneous and 

 therefore may well be called a myth. Logically 

 and historically the desirability of those experi- 

 ments has been derived from the theory, as will 

 be seen in the text. Jeffrey bases his arguments 

 upon the well-known researches of Greerts concern- 

 ing the partial sterility of many of the members 

 of the natural family of the Onagracece. Geerts 

 found that in almost all the genera of this family, 

 including all their species as far as investigated, 

 the ovules are for one half in a rudimentary con- 

 dition, which excludes the possibility of their being 

 fertilized, whilst about one half of the pollen 

 grains is sterile. This double character has there- 

 fore persisted during the pedigi'ee-evolution of al- 

 most this whole family. In contradiction with 

 Geerts, Jeffrey considers it to be an indication of 

 a hybrid condition. If this were true, almost the 

 whole natural family of the Onagracece would 

 have evolved in a hybrid condition and (Enothera 

 LamarcTciana would follow the rule. It remains 

 doubtful, however, how this hypothesis could ex- 

 plain the high degree of mutability of 0. LamarcTc- 

 iana, since the majority of the supposed hybrid 

 species do not show signs of such a condition. 





