206 
POPULAR SCIENCE REVIEW. 
Hydrostatic Pressure in Vegetable Cells . — In a recent number of the 
(l Botanische Zeitung,” there is an abstract of a communication made by 
Professor Pfeffer to the botanical section of the Association of German 
Naturalists and Physicians, at Graz, 1875, on the subject of the origin 
of high hydrostatic pressure in vegetable cells. This pressure, amounting 
sometimes to several atmospheres, even where there is only slight con- 
centration of the fluid contents of the cells, led him, on theoretical 
grounds, to refer it to the molecular condition of the primordial utricle. 
This conclusion was confirmed by experiment. With contraction of the 
molecular interspaces resistance to filtration increases, and likewise the 
pressure which is brought about endosmoticallv. 
How long do Seeds preserve their Vitality ? — This question, which has been 
often answered before, has been taken up by Herr Hoffmann, who, in a series 
of papers in the “ Botanische Zeitung,” gives his view of the matter, and 
describes experiments with loss, a diluvial earth found in the valley of the 
Bkine. When the railroad station Monsheim (at Worms) was built, the 
earth was dug away to a depth of twelve feet. Some of the loss was taken 
with necessary precautions, and securely sealed until the following spring 
(1865). In May twenty-four flower pots were half-filled with manure 
which had been heated in order to destroy any seeds present, and on this 
substratum some of the loss was placed, leaving an air-space above, of two 
inches, and each pot was covered by a glass disc which had a bit of wood 
under one edge to allow access of air. The surface of the loss soon had 
plenty of ferns and mosses, just like those which are so abundant in all 
greenhouses. A few phaenogamic plants came up ; four which could not 
be determined accurately were supposed to be Vaccinium myrtillus, a second, 
a Chrysanthemum Leucanthemum ; afterwards a third came up, a Galium , 
and finally an Fquisetum. A second series of experiments, conducted with 
greater care to exclude all waifs, gave wholly negative results. Some 
moulds, a coat of moss, and a single grass,' [Festuca pratensis, were the only 
plants within the bell-jars. 
The Origin of Fairy-rings. — In 11 Grevillea ” for March it is stated that in 
a recent communication to the Linnean Society Dr. J. H. Gilbert draws 
attention to the fact that, according to published analyses of various fungi, 
generally from one-fourth to one-third of their dry substance consists of 
nitrogenous matters. In fact, fungi would appear to be among the most 
highly nitrogenous of plants, and to be also very rich in potass. Yet the 
fungi have developed in 11 fairy-rings ” only on the plots poorest in nitrogen 
and potass in such conditions as to be available to most other plants. They 
flourish strikingly on two plots only, in neither of which either nitrogen 
or potass is applied as manure, on which the development of grasses is 
extremely restricted, and their limited growth is due to a deficient available 
supply of nitrogen, or of potass, or of both, and, where the completion of 
the Leguminosae is also weak, in the absence of a more liberal supply of 
potass. The questions obviously arise whether the greater prevalence of 
fungi under such conditions be due to the manurial conditions themselves 
being directly favourable for their growth, or whether other plants — 
especially grasses— growing so sluggishly under such conditions, the plants 
of the lower orders are the better able to overcome the competition and to 
