1910] CURRENT LITERATURE 235 
Jeaves are placed in 2/1000 acid for 24 hours, and then treated with caffein 
solution, no tannin is precipitated; while the controls kept in water show a 
heavy precipitate. The acid solution showed a strong tannin test with iron salts. 
and that they gradually diffuse out. In strong acids he finds 2/6400 the 
critical (minimum) concentration for inducing marked permeability. This is 
the concentration at which KAHLENBERG and TRUE found growth to cease. 
CzAPEK believes the stoppage of growth is directly due to reduced turgor, 
resulting from the induced permeability of the protoplasm to contained sub- 
stances. He recognizes that injuries appear in concentrations below the critical 
concentration for permeability. Various other substances give similar results. 
The critical concentration for phenol is 0.58 per cent or 2/16; for resorcin, 
di-hydric phenol, 2.85 per cent or 2/4; for pyrogallol tri-hydric phenol /4. 
Among alcohols, the critical concentrations were methyl 15 per cent, ethyl 
10-11 per cent, normal and iso-propyl 4—5 per cent, iso-butyl 1-2 per cent, 
amylo.5 percent. In acetic acid the critical concentration is below that deter- 
mined by its acid properties. The effect of external conditions upon the perme- 
ability of protoplasmic and other plant membranes is a subject that deserves 
much attention from plant physiologists. Animal physiologists are teaching 
us much in this field —WILLIAM CROCKER. 
Morphology of Sciadopitys.—Lawson”? has published an account of the game- 
tophytes and embryo of Sciadopitys, one of the peculiar conifers of eastern Asia. 
The microspores are binucleate at shedding, and are received upon the so-called 
pollen cushion, which is the tip of the nucellus differentiated into a loose tissue of 
large thin-walled cells. During the first season only one more division occurs, 
that of the generative cell into the body cell and a free stalk nucleus. In the next 
season the body cell passes toward the tip of the pollen tube, which has entered 
an archegonial chamber, and there produces two unequal male nuclei. The 
formation of the megaspore tetrad is peculiar. The division of the mother cell 
nucleus is not accompanied by wall formation; but the subsequent division of 
the two daughter nuclei is; so that the tetrad comprises three cells, the middle 
one of which is binucleate. In these divisions the chromosome numbers prove 
to be 8and 16. The innermost megaspore is the functioning one, enlarging very 
much, and becoming invested by the usual zone of nutritive cells. The female 
gametophyte is developed as in the majority of conifers, and there are four or 
six archegonia, each with its own investment of jacket cells and a deep archegonial 
chamber. A ventral nucleus is formed, but no ventral canal cell. In the develop- 
ment of the embryo, the free nuclei pass to the base of the egg at the four-nucleate 
stage, and the proembryo finally consists of three tiers of cells and one tier of free 
nuclei toward the egg cytoplasm. The middle tier of cells becomes the ae 
while the embryo- -forming tier becomes a mass of at least sixteen cells.—J. M. C 
° Lawson, A, ANSTRUTHER, The gametophytes and embryo of Sciadopitys ver- 
ticillata, Annals of Botany 24:403-421. pls. 29-31. 1910. 
