2 
74 BOTANICAL GAZETTE [JANUARY 
mobile, and are aggregated about the nucleus. In about twenty-four hours more, 
however, they become statoliths and fall to the bottom of the cells. During this 
time the original tip has been losing its starch, and there is a period of from forty- 
eight to seventy-two hours in which the old tip has lost its starch and the new 
tip has none in a movable form. During this period the roots are ageotropic. 
In ferns the root-tips do not regenerate. Tips cut off transversely just back 
of the apical cell are unable to organize a new one, though they may continue 
growing for several weeks. As the statolithic starch is in the root-cap, and this 
does not regenerate, such roots remain ageotropic. 
Besides the discussion of the experiments, a number of chapters are devoted 
to a discussion of such topics as the influence of external conditions on regener- 
ation, polarity and regeneration, growth and regeneration, purposefulness of 
regeneration, relation between geotropism and the presence of statocytes, and 
other interesting topics connected with regeneration. 
As the root-tip regenerates from so many kinds of injuries that could never 
occur in nature Némec considers that at least in the great majority of cases the 
capacity could not have arisen because of its utility. The immediate stimulus, 
he thinks, does not lie among nutritive changes, or arise from the wound, but is 
a phenomenon of correlation, due to the breaking of the connection between the 
vegetative tip and the root meristem.—W. B. McCattium. 
Plant histology. 
CHAMBERLAIN has revised and rewritten much of his Methods in plant 
histology,+ adding several new chapters, elaborating and in many instances 
shortening the processes. Several new formulae are given for killing and fixing. 
e paraffin method has been notably improved and the celloidin method has 
been treated at greater length. A method for embedding in soap is also given. 
The new chapters deal with microchemical tests, free-hand sectioning, special 
methods, the use of the microscope, and micrometric methods involving the use 
of the camera lucida. A very important new chapter deals with methods of 
staining filamentous algae and fungi and mounting them in Venetian turpentine. 
An abstract of the methods of PFEIFFER and WELLHEIM is given, together with 
such modifications as have been found to give successful preparations. Delicate 
forms like Vaucheria can be carried through the stains and finally mounted in 
Venetian turpentine without showing the least trace of plasmolysis, and even if 
slight plasmolysis should occur it can be corrected by manipulation of the mount- 
ing medium. Preparations made by this method are exceedingly brilliant and 
show a wealth of detail not possible with other methods. For example, the two 
nuclei in zygospores of Spirogyra can be readily seen with a low magnification. 
The Venetian turpentine method, which gives preparations requiring no sealing 
and as hard and durable as balsam mounts, should almost entirely replace the 
glycerin method. 
4 CHAMBERLAIN, CHARLES J., Methods in plant histology. pp. x+262. 7gs- 88. 
Chicago: The University of Chicago Press. 1905. Net $2.25; postpaid, $2-39- 
