436 PRIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 



under the influence of a surrounding electrical current, and an appli- 

 cation of the phenomenon to what takes place in a bar of iron under- 

 going magnetization. 



10. Exact experimental researches are required in order to ascer- 

 tain to what extent the dispersion in transversal radii of the particles 

 of a thread of metal by an electric discharge, described and figured 

 by Van Marum in the Memoirs of the Teylerian Society, is analogous 

 to the stratification of the light in rarefied gases, and ought to be 

 attributed to the same cause. 



11. Notwithstanding the experiments of Arago, uncertainty still 

 exists as to the state of polarization of diffused light. The society 

 requires new experimental researches, as complete as possible, as to 

 the nature of the polarization both of diffused light and of light ra- 

 diated from incandescent bodies. 



12. What is the nature of the foreign bodies observable in some 

 diamonds ? Do they belong to the mineral or vegetable kingdom ? 

 Researches upon this question, even though they apply only to a sin- 

 gle diamond, will be crowned should they lead to any interesting 

 result. 



13. As the development and first habitat of the Bothriocephalus 

 latvs (Taenia lata, L.J are as yet unknown, the society suggests re- 

 searches which shall elucidate the natural history of this entozoon 

 from the egg to the perfect state. 



14. The researches of Kramer have made it known that visual 

 adjustment depends upon a change of form in the lenses of the eye, 

 but the mechanism by which this change is effected is not yet well 

 known. The society requires new researches upon this subject, to be 

 founded on the comparative anatomy of the apparatus which serves 

 to produce the accommodation. 



15. The society requests researches into the nature of the sub- 

 stances contained in the watery vapor produced by the respiration 

 of man in a state of health and of the lower animals. It is desira- 

 ble that these researches "should, if possible, be extended to the 

 substances exhaled in some diseases, especially contagious ones; that 

 they should not only be chemically analyzed, but examined as to 

 their noxious effects upon animals. 



The society has this year propounded the following questions, and 

 requests replies before the 1st of January, 1863: 



1. The fishes of the Indian archipelago have been the objects of 

 the researches of a learned Dutch author. The society desires that 

 the other vertebrates of these islands, and especially those of Borneo, 

 Celebes, the Moluccas, and, above all, those of New Guinea, should be 

 subjected to a similar examination. The gold medal will be awarded 

 to the naturalist Avho shall send to the society either the description 

 of any new species of mammifers, of birds, or of reptiles of these 

 islands, or a memoir containing new and remarkable facts concerning 

 the structure and habits of some of these animals. 



2. The society requires a determination, as exact as possible, of 

 the errors of Hansen's Lunar Tables, by the occultations of the 



