428 BOTANICAL GAZETTE [NOVEMBER 
growth and are brought about by the contraction of the concave side, while a 
class of movements where position is secured slowly, as heliotropic and geo- 
tropic curvature, are directly associated with growth and are brought about 
by elongation of the convex side. In Vassifloree the region of maximum 
growth never coincides with the region of maximum irritability. 
The morphological nature of tendrils is various, and the assumption that 
they may have various methods of producing movement is well made. 
chief study has been given to tendrils of Passifloreze and Cucurbitacez, which 
have similar structure. It is found that the pull of a stimulated tendril amounts 
to less than one-half gram, while that of a free coiling tendril is twenty to sixty 
times as great. In the first case rapidity of movement is the essential feature, 
and in the second the production of strains. By a variety of studies, includ- 
ing plasmolysis, it was ascertained that tendril movement in the two families 
named is always due to shortening of the concave side, a point which has 
been much in controversy, : 
The author brings support from various sources, including anatomical, 
for his conclusion that the cause of coiling resides in the irritability of 
protoplasm of the concave side, by which the protoplasts are render 
more permeable, water passing into the intercellular spaces, thus allowing 
the previously stretched cell walls to contract. Space does not permit men- 
tioning other parts of the investigations, 
A summary of present knowledge on the physiology of color in plants’ 
shows that non-green colors convert the sun’s rays into useful heat and in 
some parts of the plant promote transpiration, or are occasionally waste 
products of metabolism. Colors in some cases, as is well known, also hold 
relation to insect pollination and to protection from injury. Chlorophyll is 
also to be included as a very useful color. 
The influence of carbon dioxide on the living protoplasm * appeafs sae 
be characteristic. Its effects do not résult from the simple exclusion of Das 
gen, but its action is upon the nutritive processes. Its stimulating action, ! 
any, appears to be small.—J. C. A 
> 
oD 
ITEMS OF TAXONOMIC INTEREST are as follows: Five new North pea 
can species of Saxifraga have been described by Dr. John K. Small. Ve 
good figure of the very rare Berberis Nevinit, from the sandy plains neat 
Linden. Professor E. L. Greene has issued another fascicle of 
noteworthy species, describing two new species of Ranunculus, ga 
’ Pop. Sci. Monthly 49:71. 1896 ; Science 4:350. 1896. 
* Science 3:689. 1896. Jour. Bot. 343411. 1896 
* Bull. Torr. Bot. Club 23: 362. 1896.  Pittonia 3 :91-98. 189% 
*° Garden and Forest 9:415, 18096. 
