G. GENERAL NATURAL HISTORY AND ZOOLOGY. 275 



thicknesses, apertures, etc., previously indicated by theory. 

 Indeed, Helmholtz himself relates the failure of an attempted 

 improvement which he thought himself justified in inferring 

 theoretically. The whole paper is worthy of careful study, 

 and certainly every thing which theory can give us to aid in 

 arriving at more satisfactory conclusions should be cordially 

 welcomed. Proc. Brit. Natural. Soc, Neio JSeries, I., Part 3. 



PRESERVATION OF ENTOMOLOGICAL SPECIMENS. 



M. Felix Plateau having recommended the use of yellow 

 glass in the windows of rooms containing entomological 

 collections, as a means of preserving intact the natural col- 

 ors of the specimens, M. Capronnier, of the Entomological 

 Society of Belgium, made some experiments to determine 

 the value of this suggestion. He made five small square 

 boxes, each covered with a pane of yellow, violet, green, 

 blue, or colorless glass. He then fixed in the middle of each 

 box one of the inferior wino-s oi Eiichelia Jacobece., which are 

 of a deep carmine color, uniform in tone. Each wing was 

 partly covered with a band of black paper, and their position 

 was so arranged as to leave exposed successively each of the 

 parts during a period of fifteen, thirty, and ninety days. 

 The result was as follows: Colorless Glass. The carmine 

 tint visibly attacked after exposure of fifteen days ; altera- 

 tion more sensible after thirty days ; after ninety days the 

 carmine had passed into a yellowish tint. Blue. The same 

 results as with colorless o'lass. Green. A chanixe indicated 

 on the thirtieth day ; on the ninetieth day the alteration 

 was marked. Yelloic. After ninety days the carmine color 

 almost intact. M. Capronnier accordingly concludes that a 

 yellowish color should be preferred in every arrangement of 

 an entomoloo-ical room. 



a 



PARTHENOGENESIS IN VERTEBRATES. 



Although the phenomenon of parthenogenesis, or develop- 

 ment of the embryo, without contact with the male element, 

 lias been of late well observed and appreciated among the 

 invertebrates, it has been supposed that the vertebrates, as 

 a group, formed an exception. Recent experiments by 

 Moquin-Tandon, confirm the observations of Bischoff and 

 Leuckart upon tlie eggs at least of tlie frog. In a recent 



