746 



SCIENCE. 



[N. S. Vol. XXIII. No. 593. 



NoBMAN A. Wood : ' Twenty-five Years of Bird 

 Migration at Ann Arbor.' 



NonMAN A. Wood : ' The Bird Life of Ann 

 Arbor, Michigan, and Vicinity.' (By title.) 



E. H. Fkothingiiam : ' Notes on the Birds of 

 the Michigan Forest Reserve.' 



R. A. Brown : " A Topographical Study of the 

 Birds of the ' Overflow,' at Ann Arbor, Mich." 



Chas. C. Adams : ' An Ecological Survey of 

 Isle Royal, Lake Superior.' 



Otto McCeeaby : ' The Ecological Distribution 

 of the Birds on Isle Royal.' 



Max M. Pbet: 'The Fall Migration of Birds on 

 Isle Royal.' (By title.) 



Professor Walter B. Barrows, president of 

 the academy and of the club, gave his presi- 

 dential address before the academy, on ' Facts 

 and Tancies in Bird Migration' in the new 

 lecture room of the physical laboratory on 

 Thursday evening. 



A business meeting was held in the after- 

 noon in the office of the curator of the uni- 

 versity museum. The following officers were 

 elected for 1906-7. 



President — Walter B. Barrows, Agricultural 

 College. 



First Vice-president — J. Claire Wood, Detroit. 



Second Vice-president — Edward Arnold, Battle 

 Creek. 



Third Vice-president — Norman A. Wood, Ann 

 Arbor. 



Secretary — Alexander W. Blain, Jr., Detroit. 



Treasurer — Frederick C. Hubel, Detroit. 



Editor of the Bulletin — Walter B. Barrows. 



Associate Editors — Wm. H. Dunham, Kalkaska; 

 R. A. Brown, Kalamazoo. 



The meeting adjourned to meet at the De- 

 troit Museum of Art on May 4, 1906. 



Alexander W. Blain, Jr., 



Secretary. 



DISCUSSION AND CORRESPONDENCE. 



THE FALLACY OF THE MUTATION THEORY. 



Dr. C. H. Merriam has lately pointed out^ 

 that mutation in de Vries's sense is not a 

 species-forming factor, and that it is rarely, 

 if at all, observed among living animals. 

 Major T. L. Casey objects'' to this sweeping 



' Science, February 16, 1900, p. 241, chiefly pp. 

 256 and 257. 



= Science, April 20, 1906, p. 632. 



condemnation of de Vries's theory, and be- 

 lieves that there ' may be a good deal ' in the 

 latter. 



I only can endorse Merriam's view, and 

 want to go on record as condemning even 

 more emphatically the mutation theory for the 

 following reasons : 



De Vries claims that the process of muta- 

 tion forms new species, and that the individual 

 mutations (mutants) are species. In order 

 to demonstrate this, he has made a number of 

 experiments, in which he tries to show that 

 the mutations breed true, and he uses this fact 

 as a test for the specific value of the muta- 

 tions. No other test is admitted, or even 

 mentioned, by him. 



This shows at a glance that de Vries's con- 

 ception of the term species is all wrong, that 

 he does not know what constitutes a species, 

 in spite of his lengthy discussion of this term. 

 Of course, it is generally admitted that species 

 should breed true: but this is also a necessary 

 character that belongs to the concept of va- 

 riety. What distinguishes species from vari- 

 ties is the fact that a species is not connected 

 by intermediate or transitional forms vnth the 

 most closely allied species. This latter prin- 

 ciple is the one raade use of exclusively (if 

 possible) by systematists, botanists as well as 

 zoologists. In many cases, indeed, it can not 

 be used on account of the insufficiency of our 

 knowledge; but under such conditions new 

 species are always described with the tacit 

 understanding that the demonstration of the 

 existence of intermediate forms will reduce 

 them to the rank of varieties. 



De Vries has failed entirely to take notice 

 of this fundamental principle, and to show 

 that his elementary species and his mutations 

 are not connected by intermediate forms with 

 each other. But looking over the instances 

 introduced by him, we see that such inter- 

 mediate forms are recorded by de Vries him- 

 self, and I know from personal experience that 

 such are present among several of the poly- 

 morphous genera mentioned by him {Violaj 

 Draha) . 



Further, according to the experimental 

 records on (Enothera, given by de Vries, I 

 can not see how he is in a position to main- 



