158 



SCIENCE 



[N. S. Vol. XXIX. No. 734 



renewed attention to the limitations, from a 

 physical standpoint, of the form of "interpola- 

 tion formulae " usually employed in the represen- 

 tation of natural phenomena. 



16. Mr. H. W. Fisk considers the formula for 

 latitude, 



<t>=-'li — p cos t + ip' sin 1' sin' t tan A, 

 from Chauvenet's I., § 176, and the formula for 

 azimuth, 



4. = p sin * sec 4- p- cos tan sin t cos t sin 1', 

 from Jordan, " Zeit und Orts-Bestimmung," p. 

 122. The first terms of these formulas are readily 

 computed. The last terms, called correction terms, 

 are arranged as a set of curves from which the 

 value is quickly taken by inspection. The geo- 

 graphical limits within which this method may be 

 used, as well as the expected accuracy under dif- 

 ferent conditions are discussed. Attention is 

 given to the change in correction terms due to 

 the progressive change in the value of p. 



The general committee elected Professor E. W. 

 Brown, Yale University, vice-president and chair- 

 man of the section. Professor G. A. Miller, Uni- 

 versity of Illinois, continues in office as secretary. 

 The section elected Professor G. B. Halsted, coun- 

 cilor; Professor Winslow Upton, Ladd Observa- 

 tory, as member of the sectional committee for 

 five years. 



G. A. MiLLEB, 



Secretary of Section 

 Univeesitt of Illinois 



SOCIETIES AND ACADEMIES 



THE WASHINGTON ACADEMY OF SCIENCES 



The fifty-first meeting of the Washington Acad- 

 emy of Sciences was held at Hubbard Memorial 

 Hall, January 5, 1909. Dr. L. O. Howard pre- 

 sided. 



Dr. E. B. Poulton, F.R.S., Hope professor of 

 zoology in the University of Oxford, delivered an 

 address on "Recent Researches on Mimicry and 

 Seasonal Forms of Butterflies," of which he has 

 kindly furnished the following abstract: 



The lecturer explained the theory of mimicry 

 proposed by H. W. Bates, showing in illustration 

 some of the figures from the plates of the original 

 monograph read before the Linnean Society of 

 London, November 21, 1861. In these, as in most 

 of Bates's examples, Pierine butterflies, presumed 

 to be palatable to enemies, were seen mimicking 

 the unpalatable Ithomiine (Helioonine) butter- 

 flies from the same localities. Succeeding illus- 

 trations exhibited oriental Pierine butterflies of 

 the genus Delias acting as models instead of 



mimics, and beautifully resembled by moths of the 

 subfamily Chalcosiinse (Zygsenidae) — themselves 

 admitted to belong to a group defended by its 

 unpalatability. Such examples are of course in- 

 explicable by the theory of Bates, but receive an 

 interpretation on the hypothesis of Fritz Mueller, 

 which supposes that the resemblance between dis- 

 tasteful forms has been gained in consequence of 

 the saving of life effected by a lessened amount 

 of experimental tasting by enemies. That the 

 same Muellerian principle holds in other groups 

 is seen in the numerous and varied distasteful 

 forms which mimic the African Lycid beetles and 

 by resemblances between well-defiiied wasps of 

 ditterent groups in the same locality. 



The alternative between a Batesian and Muel- 

 lerian interpretation may be approached from an- 

 other point of view. In the case of a distasteful 

 butterfly invading a new country we may enquire 

 whether the indigenous species influenced by it 

 are well concealed and presumably palatable, or 

 conspicuous and presumably distasteful. The two 

 large Danainse of North America are especially 

 interesting from this point of view. Formerly 

 placed by Moore in two genera peculiar to the 

 new world, Anosia and Tasitia, recent examina- 

 tion has shown that they are congeneric with each 

 other and with the more dominant old world 

 Salatura and Limnas. All four genera certainly 

 sink to Danaida. The old world forms are more 

 numerous and are far more extensively mimicked 

 than those of the new. They, furthermore, enter 

 into mimetic relations with other Danavnw. The 

 American species of Danaida, on the other hand, 

 are only mimicked by a single Nymphaline species 

 in the north. They extend through South America 

 beyond the southern tropic without entering into 

 any relationship with the indigenous butterfly 

 fauna, except the possible incipient mimicry of a 

 form of D. plexippus by an Aetinote, one of the 

 Acraemse. It may be inferred from these facts that 

 Danaida is an old world Danaine genus which 

 has reacned the new world in comparatively re- 

 cent times and has entered South America by way 

 of North America. 



The well-known mimic of D. plexippus, Basil- 

 archia (Limenitis) archippus has been evolved 

 from B. {L.) arthemis — ^with a pattern of the 

 Limenitis type found through the temperate cir- 

 cumpolar belt. In the theory of the production 

 of mimetic resemblance by climatic or other local 

 influences the invading Danaine should have been 

 influenced to produce a Limenitis pattern in the 

 northern temperate zone. It should have been the 

 mimic instead of the model. The black and white 



