Notices of Botanical Literature. 43 
long had in preparation; and has recently published two brief 
but important articles bearing upon this subject. One of them, 
“Sur les causes qui limitent les espéces végétales da coté du nord, 
en Hurope et dans les régions analogues,” communicated to the 
French Academy of Sciences, (published in Ann. Sci. Nat., for 
Jan., 1848.) deduces the law, that each species having its polar 
limit in central or northern Europe, exteuds as far northward as 
it receives a certain fixed amount of heat, calculated (not from 
the mean temperature of the year but) between the day when 
there commences and the day that ends a certain mean tempera- 
ture. The other, ‘“‘ Du mode d’action de la chaleur sur les Plantes, 
et en particulier de l’effet des rayons solaires” (Bib. Univ. Geneve, 
March, 1850), investigated by making growing plants themselves 
Serve as the measure of solar action, goes to show that Boussin- 
gault’s method of estimating the sum of heat necessary to pro- 
duce a certain result in a given species, requires still further modi- 
fication ; and that, as might be inferred, the effect of the sun on 
the thermometer, is far from being a true measure of its action 
on vegetation. 
Shortly after the lamentable death of Prof. Kunth* (which oc- 
curred on the 22d March, 1850, at the age of 62), appeared the 
fifth volume of his Enumeratio Plantarum, comprising the Or- 
ers Asparaginee, Smilacea, Dioscoreacea, and Amaryllidacee, 
with some small groups nearly allied to these. . Its merits appear 
to be about the same as of the preceding volumes. 
The Annales Botanices Systematice of Walpers, has not gone 
beyond the first volume. 
Since Endlicher’s death, a fifth supplement to the Genera 
ra ormation), Prof. Unger has just published a series of fourteen | : 
landscape plates, in imperial folio, of high artistic 
7 A biographi is distinguished botanist, from the 
nf phical memoir of this distinguished botanist, from th 
— de Jussieu, will be found in the Annales des Sciences : 
