28 
the algz eliminate the silica from solution does not seem to be 
known, but from what the author says, it is evident that he con- 
siders it due directly to the action of the plant’s vitality in some 
way, and he says that both the filaments and their slimy 
coverings are formed of gelatinous silica. ‘In general, it may 
be stated that the large vase and pillar-forms found in the alga 
pools can be produced only by a concurrent life and death of 
these plants; the outer layers continually growing, the innermost 
dying.” Besides the sinter formed from the jelly-like masses there 
are fibrous sinters formed by Calothrix gypsophila and Leptothrix 
laminosa. On the lower part of the slope, below the Madison 
Plateau, a moss (Hypuum aduncum, var. gracilens) seems to act 
as an agent in forming sinter, and we are told that “ this sinter is 
not formed by evaporation * * * but is due to the abstraction of 
silica from the water by the mosses * *.” The difference between 
the unaltered sinter, due to simple evaporation of the water and 
that due to the influence of vegetable life, is quite marked; the 
former being translucent or vitreous, while the latter is opaque 
and often chalk-like in appearance. Diatoms are abundant in the 
cooler waters and form the ooze of the geyser basin marshes. 
The author has certainly proved a far greater importance for plant 
life as a rock-building agent than we formerly knew of and it is 
quite possible that similar studies in other localities would yield 
equally interesting results. 
A, 
Gunnera.—Eine Brasilianische (Gunnera manicata, Linden.) 
W. Schwanke. (Engler’s Bot. Jahrb. xii. Beiblatt nr. 28, 1-3, 
illustrated). : 
Hepatice Africane Nove in Insulis Bourbon, Maurice et Mada- 
gascar lecte. F.Stephani. (Bot. Gaz. xv. 281-292. Pi. 
XVII-XIX). 
Twenty-three new species are described. : 
Hepatice—List of Canadian. WW.H. Pearson. (Geol. and Nat. 
Hist. Surv. of Can. Montreal, 1890. Pamph. pp. 31, Pl. XII). 
Professor Macoun is to be congratulated on having secured 
so competent and conservative a student as Mr. Pearson to work 
up his collections of Canadian liverworts, and we learn with 
pleasure that the only new species described, /rudlania Selwyn- 
