74 Intelligence and Miscellaneous Articles. 



In the Pliocene flora the tropical types have totally disappeared ; 

 but a few subtropical species are still found. The plants of the 

 warm region predominate ; those of the temperate zone continue 

 to increase in number. The American character remains very 

 marked. 



Finally, in the Quaternary flora the subtropical species and 

 those of the warm region have entirely disappeared, even in Italy. 

 Most of the plants are identical with those now living in the same 

 regions. Some exotic and extinct types, however, are found in it, 

 and as it were an echo of America. 



"We see, then, in short, how the present flora has issued little 

 by little from the tropical Eocene flora — how, by degrees, the forms 

 of warm climates, then those of temperate ones were added to the 

 tropical forms, which retired before them in the same proportion, 

 leaving their rivals to constitute alone the modern vegetation. 

 "We see also that in the beginning it is the Indo-Australian types 

 that compose the flora; but as the element which is gradually 

 added has a very decided American complexion, the vegetation 

 assumes, in proportion as it is augmented, a more and more 

 American character, which afterwards wears off, and at the diluvial 

 period again, to a great extent, disappears. 



All these researches, both upon the fossil plants and animals, 

 coincide in obliging us to regard the climate of Europe generally 

 as warmer during the Tertiary period than at the present time — 

 as subtropical, similar to that of the southern United States, and 

 specially Louisiana. But in a given locality there were differences 

 according to the periods, and at a given period differences accord- 

 ing to the localities. Thus, at the Upper-Eocene period, the mean 

 temperature in any part of Europe was probably 13 or 14 degrees 

 higher than it is now in the same locality ; at the period of the 

 Lower Miocene the difference was only 9 degrees, during the 

 Upper Miocene 7 ; and in the Pliocene period it fell to 3 degrees. 

 And thus, again, at any one period the climate was fa - : from being 

 the same in the different parts of Europe : there was a distribution 

 of the heat according to certain zones; and all the researches, 

 especially the study of the fossil plants of Iceland (which is par- 

 ticularly instructive in this respect), agree in demonstrating that 

 that distribution took place in precisely the same manner as at the 

 present day. — Annates cle Chimie et de Physique, October 1878, 

 t. xv. pp. 157-161. 



ON THE DIFFUSION OF LIQUIDS. BY J. STEFAN. 



In this memoir the observations made by E. Voit and Hoppe- 

 Seyler on the diffusion of sugar-solutions, by the saccharimetric 

 method, are first discussed, and compared with the theory of dif- 

 fusion advanced by Pick. Of these experiments those instituted 

 by Hoppe-Seyler on the diffusion of urine-sugar accord best with 

 the theory ; and from them the coefficient of diffusion can also be 

 determined, which is found =042, taking the centimetre as the 

 unit of length, and 24 hours as the unit of time. 



Hoppe-Seyler's observations, made with another saccharimeter, 



