124 



SCIENCE 



[N. S. Vol. XLIII. No. 1100 



with varied climate and a great diversity 

 of conditions, mountains and valleys, for- 

 ests and open plains, left through long ages 

 entirely to its own resources, was the 

 closed arena of rapid development diver- 

 gent from the rest of the world. The re- 

 sult is plainly obvious now. Though the 

 elevation of Central America and the 

 Isthmus into land joined Notogeea with the 

 northern continent and the way of migra- 

 tion thus opened led to an extensive in- 

 fusion of northern elements in the south- 

 ern fauna. South America still remains, 

 after Australia, the most peculiar region 

 of the earth. 



North America had quite a different fate ; 

 its connection with the south was a mere 

 episode which led to the transitory recep- 

 tion of a considerable number of Notogseau 

 forms and the permanent establishment of 

 a very few. Its oft-repeated connection 

 with the Old World was far more signifi- 

 cant from the zoological point of view, for 

 that maintained the essential community 

 of mammalian life all over the northern 

 hemisphere. To this connection it is due 

 that North America is a part of Arctogsea 

 and that its Arctic and Boreal zones are 

 inseparable from the great Holarctic Re- 

 gion of Europe and Asia. In the Pliocene 

 and Pleistocene, North America was the 

 meeting-ground of currents of migrating 

 animals, from the west and from the south 

 and for a time the fauna was of an excep- 

 tionally composite character. Old World 

 and NotogEean elements mingling with the 

 richly variegated indigenous stocks. But 

 this condition was much modified by the 

 Pleistocene extinctions which almost en- 

 tirely exterminated the invaders from the 

 south and greatly reduced the number of 

 autochthonous forms. The destruction of 

 immigrants from the Old World was less 

 extensive and thus the zoological relations 

 of North America in the Pliocene and 



Pleistocene were quite different from what 

 they are now. 



The problems which deal with the pos- 

 sible connections of South America with 

 continents other than North America and 

 especially with Africa and Australia, are 

 extraordinarily interesting from many 

 different points of view, but there is no 

 time to enter upon a discussion of them 

 here, nor are they altogether germane to 

 the subject before us, which is the zoolog- 

 ical relations of the western hemisphere as 

 conditioned by the Isthmus of Panama 

 and its geographical history. 



W. B. Scott 



Princeton University 



THE NEEDS OF APPLIED OPTICS' 



We have formed this Association for the 

 Advancement of Applied Optics because we 

 believe that the interests of all branches of 

 applied optics may be materially furthered 

 by such an organization. It seems fitting, 

 therefore, to devote this first meeting to a 

 discussion of the needs of applied optics 

 and to the outlining of plans for securing 

 the advancement desired. 



The interests of every one who uses light 

 are affected by applied optics in its broader 

 interpretation. In the formation of this 

 society we have invited the cooperation of 

 all who are directly interested in the studj'' 

 and use of light and of optical instruments 

 of all kinds. We therefore include, among 

 those whose interests we aim to serve, as- 

 tronomers, designers of optical instruments, 

 illuminating engineers, photographers, oph. 

 thalmologists, photometrists, colorists, pe- 

 trologists, microscopists and all investiga- 

 tors of optical problems. The field to be 

 covered is broad and the interests affected 

 many and diverse. 



1 An address inaugurating the formation of the 

 Association for the Advancement of Applied Op- 

 ties delivered at the first meeting held in Eochester, 

 January 4, 1916. 



