1903] CURRENT LITERATURE 311 
scheme of phylogeny is to be counted a step in advance, even though it be 
replaced by another imperfect one. The authors are, therefore, quite justified 
in giving the concise review and criticism of current views of the phylogeny 
of vascular plants that is to be found in chapter xv. Very important also, 
in its bearing on this subject, is the presentation of the leading facts of the 
anatomy of the vascular plants, given in the two concluding chapters of the 
book by professor Edward C. Jeffrey, of Harvard University. 
he well arranged and efficiently complete bibliographies are sure to 
prove a most valuable feature of the book to investigators, An adequate 
series of figures has been well selected from many sources, and they are 
admirably executed, excepting perhaps the never-satisfying photomicro- 
graphs of the embryo-sac.—D. S. JOHNSON. 
Experimental morphology. 
THE LITERATURE of experimental morphology has received an important 
addition by Dr. Klebs. The present publication? is really a continuation of 
his older work (1896) on the physiology of reproduction in algae and fungi, 
and carries the theoretical as well as the experimental side of the subject of 
reproduction and development into higher plants. Beginning with a short 
history of the development of this branch of botany, from the time of Knight 
forward, the introduction proceeds with definition and discussion of such sub- 
jects as specific structure, causality, external and internal conditions, the teleo- 
logical point of view, etc. As would be expected, this author does not regard 
a teleological explanation as any explanation at all. His clear exposition of 
the purely objective method of interpretation will doubtless be a great help 
to students who have difficulty in breaking away from the sometime prevalent 
teleology. His discussion of external and internal conditions is hardly satis- 
actory, however; one feels that, after all, the division, convenient as it may 
be, is an arbitrary one. Indeed, to the reviewer it seems as though we might 
soon be able to discard both terms altogether, naming a stimulus where we 
have come to know it and confessing ignorance where it is still outside our 
knowledge. A physiology based on study of the protoplasm can hardly make 
a distinction between external and internal factors; the cell sap is physio- 
logically as much external to the organism as is the atmospheric air, and the 
protoplasm itself is probably made up of a number of different systems, often 
external to one another, and influencing one another in many ways. 
lebs describes several new and instructive experiments with Ajuga 
reptans, Glechoma hederacea, Veronica chamaedrys,and others. By darkness, 
rather high temperature, and plenty of moisture, cuttings of the flowering 
shoot of Ajuga reptans were transformed into runners, producing rosettes 
instead of the normal floral bracts and flowers. Also, a runner submerged in 
water grows erect to the surface of the medium and then returns to its hori- 
?K Eps, G., Willkiirliche Entwicklungsinderungen bei Pflanzen. pp. iv- 166. 
Jigs. 28. Jena: Gustav Fischer. 1903. 
