324 ANNUAL OF SCIENTIFIC DISCOVERT. 



species have the power of emittino^ commensurable sounds, 

 nui>i('al, and enfreudei-ed by a mechanism of wliirh museuhir vi- 

 l)ratii>n is the principal motive-pdwer; otiiers can ^ivc l)irth to 

 liri'atliiiii; SDiuiiis like those wiiicii many r('i)tiles emit; and linally 

 otliers have only tiie power of making stridulent noises, tlie tUect 

 of a coarse mechanism, such as is found in a <;reat number of in- 

 sects. It would be a misconception of the i)Iiysiol(>j^ical defini- 

 tion of the word voice, to use tiiat word for tin; jjurpose of desit^- 

 nating souTids so very diff(^rent one from another ; and especially 

 tiit^ commensurable sounds wliich fishes produce by means of 

 three organic mechanisms which have no resemblance to each 

 other." 



Vision of Fi.sh and Amphibia. — M. Plateau, of Ghent, has 

 recently publisiied a sketch (jf his researches on this subject. His 

 investi'.^ations were only extended to fresh-water fish, owing to 

 the dilliculty of procuring others in a fresh state. He finds that 

 the cornea is flattened in the centre, but that a curvature is very 

 a])parent at the l)order. The crystalline lens is always spherical, 

 and the li(|uid which tills the cavity of the eye is of tiie same, or 

 nearly the same specific gravity as water. For purposes of com- 

 parison he has examined the eyes of aquatic birds, and of frogs, 

 and of some acpiatic mammalia, and he finds that in all the cornea 

 is sensil)ly fiatt<'ned in the centre, and the cr3'staliine lens ap- 

 proaches the form (jf a sphere. In order to show that in the fish 

 vision is as distinct in air as in water, and that this distinction is 

 independent of any power of accomodation, he prepared a recently 

 removed eye iu such a manner as to show the formation of the 

 image of external ol)jcets. He found that the distances of distinct 

 vision were sensibh- the same, whether the organ was in air or 

 hnmersed in water. These experiments were made upon the 

 e\'es of two or thriic kinds of fresh-water fish and frogs. He did 

 not extend them to the eyes of aquatic birds and mammals, but 

 instances the siniilarity of structure with the eyes of fish as a proof 

 that the same principle prevails in both cases. The paper was pre- 

 sented to the Belgian Academy. 



Hie Pohjnesians and their Migrations. — M. Quatrefages has just 

 published a book on this subject. His conclusions are these : 

 " The Polynesians were not created on the spot, nor are they the 

 last remains of pre-existing populations. Voluntary migrations 

 have brought them into the archipelago of Oceaniea. From their 

 type, we may gather their origin ; it is to be found in the Asiatic 

 arcliipelago. In some of these migrations, they would fall in 

 with some families of the black race, who might have been cast 

 away on the same islands by the chances of the sea. He consid- 

 ers that none of these migrations are of a date anterior to the first 

 Olympiad ; and the great majority occurred about the commence- 

 ment of our epoch." 



Preservation of Zoological Specimens loith their Natural Colors. — 

 Mr. A. E. Verrill thus writes to " Silliman's Journal": "Star- 

 fishes may be dried, so as to retain their natural colors almost 

 unimpaired, by immersing them in alcohol of moderate strength 

 for about a minute, or just long enough to destroy the life and 



