70 BOTANICAL GAZETTE [JANUARY 
the conception of the organized, in which the elementary component particles 
maintain within certain limits definite relations to each other, although the 
structure as a whole may be highly plastic, as contrasted to the fluid 
It is to be regretted that the author did not feel warranted in evan a 
digest of the available data, such as they are, regarding the changes which take 
place in the structure of the striated muscle cell during contraction. 
In connection with the discussion of the smooth muscle, the theory of short 
waves of contraction is developed. Whereas in the striated muscle the con- 
traction wave has a length many times that of the muscle cell, in the smooth 
muscle it is but a fraction of the length of the cell. If contraction waves start 
simultaneously in all the fibrillae of a cell and keep step as they advance, the 
contraction knot of any fibrilla comes close to those of its neighbors, with a 
result that a more or less complete diaphragm is formed across the cell which, 
as it moves along, pushes the more liquid contents before it; a conception which 
HEIENHAIN made use of in accounting for protoplasmic streaming in plant 
cells, and which has not been weakened by PFEFFER’S and RHUMBLER'S 
criticisms. The same conception is applied in a convincing manner to the 
movement of granules in pigment cells, and the suggestion is made that a 
similar situation obtains in dividing cells, resulting in the zonated appearance 
- often observed in astrospheres. A further interesting application of the theory 
of short waves of contraction is made in discussing the contraction of cilia. 
The section on the nervous substance brings together in an extensive but 
easily accessible manner the leading data on this highly complicated subject, 
which is of such importance to the cell theory. The author comes out une- 
quivocally in favor of the neuron theory, a gratifying result for the adherents 
of this theory, especially since the standpoint of the author noted above wo 
have made him keen to use any possible evidence against the cell theory. In 
the introduction a word is spoken for the importance of psychic processes a5 
psychic processes in the economy of organisms and not as by-products of 
physico-chemical changes in the nerve substance. Considerable attention is 
processes in the protoplast results from the facts observed in the regeneration 
of a severed nerve fiber. Here, as in other known cases, repair proceeds from 
the nucleated portion of the cell, the other disintegrating. In the nerve fiber 
the cut surface may be a meter removed from the nucleus, so that a direct 
transportation of material from the nucleus to the region of injury is practically 
excluded, the action of the nucleus apparently being a dynamical one. The 
author also argues in favor of the ‘‘Tigroid” as a cytochromatin, an accessory 
chromatin developed in consequence of the huge cytoplasmic portion of the 
nerve cell. 
A concluding chapter discusses the filar theories of protoplasmic structures 
and related matters. 
The work contains an abundance of suggestions and information bearing 
