280 Scientific Intelligence. 
a volume of about 250 pages,—intended for schools and classes generally, 
and as an Introduction to the Manual of the Botany of the Northern 
United States,—is just published by G. P. Putnam & Co. and Ivison & 
Phinney, New York. 
e. 
Causes of the Opening and Closing of Stomates ; by Huco 
von Mout, (Botanische Zeitung, 1856, No. 40, p. 697, et seqq.)—In this 
memoir von Mohl corroborates by actual experiments the general impres- 
sion, the truth of which had not been demonstrated, that stomates shut 
when the guardian cells collapse, and open when they become turgid. 
The opening of the stomate is guar by two crescent-shaped cells, 
the guardian-cells, which generally take the following form. On their 
to form a salient protuberance. The edges of these projections unite at 
both the ends of the stomate, so as to make an orifice above the true 
the lower side of the guardian-cells, there lies in most plants another 
projection like that on the upper side, but generally smaller, by which 8 
