NOTICES OF BOOKS AND MEMOIRS. 27 
Ueber Geysirs und nebenan enstehende verkieselte Biume. Von Dr. 
tro Kuntze. ‘Das Ausland,’ 1880 passim. (Separat- 
- Abdruck.) 
Dr. Kunrzx, in the course of his study of the geysers of the 
United States and of Japan, observed that the silicic hydrate with 
which trees lying in the water are impregnated does not harden, 
woods of lesser specifie gravity than water. He distinguishes 
between silicifaction and petrifaction. Petrified trees, he adduces 
to show, s i 
quantities of the silica-holding water of geysers and hot springs 
which rises in the wood by capillarity, and evaporates gradually in 
the air. rred in 
een to some extent silicified by receiving the heavy showers 
occurring on the leeward side of geysers, as figured by Sir Charles 
Lyell (‘ Principles,’ 11th edition, vol. ii., p. 218)? Dr. Kuntze, in 
conclusion, s from his observations fresh support for his theory 
that the plants of the coal-measures floated in the sea. Aa. F 
Revision von Sargassum und das sogennante Sarqasso-Meer. Von Dr. 
Orto Kuntze. Mit einer Phototypie und einer Karte. Separat- 
Abdruck aus Engler’s botanischen Jahrbiichern, I Band, 8 Heft. 
1880. Leipzig: Wilhelm Engelmann. 
Tue ‘ Gulf-weed ” is commonly supposed to consist of a single 
species (8. bacciferum), and to be confined to a particular portion 
of the Atlantic Ocean. In this treatise, Dr. Kuntze conclusively 
shows that both these suppositions are erroneous—that not only 
does the Gulf-weed consist of several species and many varieties, 
but that itis not met with in the same spots nor in similar quan- 
