1897 | CURRENT LITERATURE — 475 
is unnecessary. The chapters on the absorption and assimilation systems 
are considerably enlarged, the former by a paragraph on the absorption of 
water by the hairs of foliage leaves. The chapter on the conducting system 
is also much enlarged, the author giving an exposition of the theories of 
water conduction and explaining the present status of our knowledge of this 
difficult and perplexing subject. Another section of the same chapter illus- 
trates the author’s idea of the dependence of form upon function, that is, 
that organs are called into existence by some special need of the plant. In 
this connection he gives an hypothesis concerning the saa manner of 
development of the different kinds of bundle 
The chapter on apparatus for special purposes contains a description of 
the various means of plant motion. The passive organs are the flying and 
Swimming tissues which are fully described and illustrated. The active 
tissues are described as hygroscopic and living, the latter including those 
through which movements are caused by outer stimuli. The tissues supposed 
to receive stimuli and those designed only for their conduction are fully 
treated. ; 
In style the book is exceedingly clear and attractive, and the principles 
upon which its method of treatment rests are now admitted by all. It is 
questioned by some, however, whether this per of tissue systems 
should be sidlectleid for the older and simpler one which is now in general 
use. The objections are that it presupposes at least a partial knowledge of 
the tissues, and that it is too extended to find a place in a text-book on general 
tany. Both of these objections have more weight perhaps in this country 
- than in Germany. It is also true that the simpler method is far more practi- 
cal for students of pharmacy and medicine, and for any others who wish only 
a general view of this branch of botany. In view of these considerations it 
would seem wiser for us, at least, to precede such a view as Haberlandt 
Presents by a general view based simply upon didactic [a 
L. Grecory. 
. NOTES FOR STUDENTS. 3 
THE action of the yeast cell during alcoholic fermentation has sheave : 
been a difficult matter for the physiologist to explain. Most writers for the 
_ last twenty-five years have considered fermentation a specific form of proto- 
_ plasmic activity, possessed by certain species of lower plants in a highly 
_ developed form. The view of Traube (1 858) and of Hoppe-Seyler, ascribing 
fermentative action to an albuminoid co secreted by the yeast cell, 
allied in its nature to the enzymes, has never found favor with botanists. 
Nageli i in his carefully considered theory of fermentation (1879) pointed out 
very important differences between the behavior of so-called organized | and 
hapa and laid ra stress: — the fact that it had 
