377 
Tur VEGETATION OF THE JuRA Lakes. 
Recherches sur i Végétation des Lacs du Jura. Par M. Ant. Maenin. 
e la Revue Générale de Botanique, aiaal 5 (1893), 
pp. ered et 803-316.) Paris: Paul Klincksi 
Iv various publications Dr. Magnin has given ae of his 
exploration of the sixty lakes of the Jura. He here brings together 
all these, and gives a complete review of his work, ‘‘in the depth, 
he e temperatur ure, the coloration, the transparency, the vegetation, 
the biological conditions, &c.,” extending from 1890 to the present 
year. 
Dr. in divides these lakes into three series, ‘‘lac normal,” 
‘lac de tourbiéres,’’ and ‘‘lac-étang,” the first of course being 
almost always the deepest, and the last usually the enews t. He 
traces out certain zones of vegetation in the first two series o 
lakes:—1, the zone of Carex; 2, of Phragmites; 8, of Scirpus; 4, of 
Nuphar ; 5, of Potamogeton ; and 6, of Characea. These of course must 
be taken in a general sense, not as strictly exact, as in early pErngs 
when the water-level is high, Charas and Nitellas will often 
gathered in the Scirpus zone (certainly in England) ; later, as tie 
flow 
even. the ppianny ies some of which (notably P. ae wi 
iver in ate water; and P ms will not survive 
seg = the air for long. In this ronan a great deal of careful 
work is yet required to work out the conditions of growth of our 
submerged water plants under unlikely conditions. 
The vegetation of these lakes is very similar to many Scotch 
ones, the only ear cn are forei apt to our Flora — a 
nN m Lange, N. Spennerianum; Char 
jurensis Hy and var. ” Magnini Hy (oth new), Nitella fablate, 
Trapa natans, and Naias major (the last in England in three 
stations; not in one, as recently reporte 
Of these, Trapa natans is decidedly the most ~ eae its 
ains were found associated with Naias major in Norfolk, and 
river for y with a dense mass of vegetation often 6 to 9 in. in 
thickness; further on by a similar growth of Potamogeton natans or 
* See Journ. Bot. 1893, p. 182. 
