414 Correspondence of J. Nicklés. 
A medal of gold, of 800 francs, is decreed each year to the work, 
rinted or in manuscript, which appears to have contributed the most to 
the Progress of Experimental Physiology. 
A gold medal of the value of 2500 francs, is offered for 1856, for 
the best work on the mode of fecundation of eggs, and the structure 
of the organs of generation, in the principal natural groups of the class 
of polyps, or of that of Acalephs. 
A large number of prizes are offered in mathematics, medicine and 
gy, and NOTHING for physics, chemistry or mineralogy ; it 
would.seem as if these sciences had no existence. It is true that the 
Academy of Sciences of Paris has little to show among the great dis- 
coveries which physics and chemistry have accomplished in these later 
action on the part of the Academy. 
son of the illustrious zoologist, and who should not be confounded with 
the botanist, M. Auguste de St. Hilaire, to whom we have above alluded. 
M. Is. G, St. Hilaire is Professor of Zoology at the Jardin des Plantes, 
and for a long time he has prepared himself for the noble work which, 
aided by several other savants and the principal great proprietors od 
France, he is about to undertake. The end of the Society is to promote 
(1) the introduction, acclimation and domestication of species of animals 
either useful or ornamental. (2.) The perfection and multiplication 
of new varieties, introduced or domesticated. The number of members 
of the Society is not limited, and foreigners may unite in it 4 
among the latter, there are already. Prince Demidoff, MM. Graélls, 
Ramon de la Sagra, Vilanova of Madrid, and a large number © Bel- 
an Dp : 
Artificial Production of Pleochroism in Crystallized Substances. 
The influence which small quantities of a foreign substance chemically 
inert, exert upon the physical properties of bodies, as their density, 
index of refraction and angle of polarization, has long been known. 
Some years since,* I showed that these causes act also on the angles 
of crystals, and at times produce modifications as great as 2 change 
f the type and system of crystallization, and thus may g seis 
dimorphism.+ Since then M. Hugard has observed facts of a similar 
* Comptes Rendus de I’Acad. des Sci., 1848. 
+ Comptes Rendus de Laurent, ete, 1850, and Annalen de Ch. et de Phys, 1858 
has 
