169 
was at the beginning of the experiment; moreover, it will repeat 
this performance as often as desired. - 
The most curious phenomenon of all, the sudden appearance 
of the air-bubbles in the cells of the annulus, causing the jerking 
motion by which the spores are scattered, is explained ie Prantl * 
in the following manner: 
The interior of the cells of the annulus is lined with a continuous 
layer of protoplasm which is thickest along the inner, thinner 
along the radial, and quite thin at the outef walls. This layer 
can be demonstrated by treating with chloriodide of zinc. (I 
obtain better results by using a concentrated solution of sugar 
and sulphuric acid). It must be assumed that this protoplasm, 
or rather some unknown substance contained in it, absorbs water 
through the cell-wall, with great avidity and force, while there 
is no plasmolysis, i.e., the cell-membrane does not permit the 
water-absorbing substance to pass out of the cell. There will 
be, consequently, great endosmotic pressure exerted on the con- 
tents of the cell, and the air which is present in it will, under 
this pressure, be absorbed by the water. On the other hand, if, 
by using glycerine, or similarly acting reagents, the water is ab- 
stracted from the cells, the first effect is that their space is dimin- 
ished, the outer wall gives way, and folds up inward, etc., but as 
soon as the endosmotic pressure is diminished so that a certain 
limit is reached, the air which had been absorbed will suddenly 
be liberated, and the volume of the cell increased correspondingly. 
In the living plant, the bursting of the sporangia and ‘the 
scattering of the spores must be explained in the same way, viz. : 
by the gradual disappearance of the water from the cells of the 
drying annulus. JosEPH SCHRENK. 
Botany at the Buffalo Meeting 
OF THE 
AMERICAN ASSOCIATION_FOR THE ADVANCEMENT OF SCIENCE, 
AUG. I8TH-24TH, 1886. ; 
The Botanical Club met at 9 a.M., Thursday, Aug. ee and 
held three subsequent meetings, Prof. J. M. Coulter in the chair; ; 
‘Dr. J. C. Arthur, Secretary. Owing to duties as see of eo 
* Berichte d. Deutschen Bot. Gesell., iv., p. 42. 
