Physiological Anatomy. 149 
controverted state of this question this seems a serious omission. In 
dealing with sense-organs for light-stimuli, an interesting view is 
put forward that the epidermal cells of the upper sides of euphoto- 
metric leaves act as lenses, tending to concentrate the light rays 
on the central part of the inner cell-walls; a shifting of the 
direction of the incident rays will then shift the spot of light from 
the centre of the inner wall, and this might act as a stimulus leading 
to a movement which would bring back the light spot to its position 
of rest. 
In the section devoted to “ Mechanisms for the conduction of 
stimuli,” intercellular protoplasmic connexions are reviewed from 
this point of view, and an account is given of the hydrostatic 
mechanism for the transmission of contact stimuli in Mimosa 
purfica, discovered by the author some years ago. 
In the account of the rudimentary conducting strand in the 
stem of Polytrichace® it is stated that there is no sheath structure 
limiting the cylinder from the cortex. This is true of the aerial 
stem but not of the rhizome-like underground stem, where an 
extremely well-marked, though incomplete, endodermis is very 
obvious. No mention is made of the radially organised root-like 
structure of this underground stem. 
We have no space to enter upon a review of any more of the 
many topics discussed by the author in this comprehensive work; 
but we can certainly assure him of the fulfilment of the hope 
expressed in the preface of this edition, that the book, now entering 
upon the third decade of its existence, may “ jung genug geblieben 
sein, urn auch fernerhin nicht nur lehrend und uberliefernd, 
sondern vor allem auch anregend wirken zu konnen.” 
THE UNIVERSITY OF LONDON ADVANCED 
LECTURES IN BOTANY. 
I ^HE second year of the three years’ scheme of these lectures, of 
which notices have already appeared in this journal has now 
been completed. 
In the Lent term a course was delivered at University College 
by Mr. V. H. Blackman, of the Natural History Museum, on “The 
Ascomycetes with special reference to the Origin of the Ascus.” 
Microscopic demonstrations were arranged to accompany the 
lectures. During the present term Dr. F. F. Blackman, of 
Cambridge, has given a course of eight lectures, also at University 
College, on “The CO.,-economy of Plants,” very largely based on 
