Laboratory Note. i 73 
appeared in 1900, has unfortunately been delayed by illness. It is 
not necessary now a days to point out to botanists the value of the 
book; suffice it to say, that like the earlier parts, this one displays 
that philosophical method of treatment, fullness of discussion and 
wealth of reference to the literature which make the Handbook a 
really monumental work. 
The first half of the second volume dealt chiefly with growth 
in general; the second part deals first with curvatures, under the 
headings of autonomous curvatures, movements of climbing plants, 
curvatures produced by mechanical and chemical stimuli, photon- 
astic, thermonastic and hydronastic curvatures ; and there is a 
special section on the movements in connexion with the opening of 
such organs as fruits, anthers, sporangia, and with the ejection of 
seeds and spores. A long chapter is devoted to tropistic curvatures 
(curvatures produced by 'a one-sided stimulus in contradistinction 
to such movements as photonastic, which are brought about by a 
general diffused stimulus) which are classified under ten heads. A 
section is devoted to the conditions of stimulation and the nature of 
the stimulation-process in the various tropisms. In relation to the 
much debated question as to the nature of the geotropic stimulus. 
Pfeffer’s view is that neither the statolith theory in general nor the 
starch grain theory of Nemec and Haberlandt in particular, can 
yet be accepted. He still considers it possible that the effect may 
be brought about by difference of pressure in the cell, nor does he 
consider the existence of a high osmotic pressure in the cell as 
any objection to the view that slight difference of pressure may so 
act. There is in conclusion a chapter on locomotor movements 
of plants and on protoplasmic movement, one on the production of 
heat, light and electricity, and a final chapter with a general review 
of the intake and output of energy by the plant. 
With this part there is also provided an index of authors and a 
subject index to the whole volume. The latter index is fortunately 
a full one, and will do something to make up for the differences of 
style and lack of co-ordination between the various parts of the 
work, which in spite of all its merits makes it by no means easy of 
reference. In this connexion it seems a pity that in the English 
edition the numerous cross-references, which also help to mitigate 
the effect of the lack of co-ordination, should, so far, have been 
largely omitted. 
LABORATORY NOTE. 
CONGO-RED AS A STAIN FOR UREDINE/E. 
Congo-Red in 1% watery solution has been found very useful 
in staining the hyphae of the Uredineae, as the cell-walls of 
the fungus are tinged a bright red, whilst the host-cells remain 
usually untouched or only take the stain very lightly. Sections 
(microtome sections were mostly used) are stained for a few (2-10) 
minutes, and the fluid is then washed off directly with alcohol if a 
strong stain is required, or with water first if only a slight stain 
