344 BOTANICAL GAZETTE [May 
hyde. GRraAFE and RICHTER (11) have lately demonstrated that 
an atmosphere bearing acetylene or carbon monoxide changes 
radically the course of metabolism in various plant organs. In 
seedlings of Vicia villosa and V. sativa and stems and tubers of 
the potato, carbon monoxide (0.038 to 0. 29 volume per cent in air) 
causes an increase in the sugar and amino content. In fatty seeds 
(squash and mustard) there is a decrease in sugar and amino com- 
pounds and an increase in glycerine and fatty acids. Acetylene 
interferes with the synthesis of sugar from glycerine and condensa- 
tion of glycerine and fatty acids to fats. 
PURE AIR LABORATORY AIR 
Cotyledon | Epicotyl Cotyledon | Epicoty! 
0.140 | 0.289 0.348 | 0.625 
The second evidence that RicHTER offers for poisons causing 
increased osmotic pressures is the fact that they often produce 
proliferation of sublenticular tissue similar to the substomatal pro- 
liferations or intumescences caused by high humidity. Very often, 
also, the lenticular protrusions, as well as other tissues, show 
guttation in the presence of poisons, which RicHTER interprets 
as indicating high osmotic pressure. Measurements of osmotic 
pressure would certainly be more to the point in the case of pea 
seedlings, though they might give less ground for philosophy and 
even a reverse conclusion. Aside from known relations to osmotic 
pressure, and only indirectly bearing on the point under discussion, 
it is well known that poisons, especially atmospheric impurities, 
produce considerable alteration in the structure and form of plants. 
The late work of GaTIN (8, 9) on the effect of tarred roads on vege- 
tation furnishes excellent examples of this. He finds that the 
fumes of tar bring about the disappearance of endodermis, altera- 
tion in the size and number of layers of cells in the cortex and other 
regions of the stem, and the transformation of doubly compound 
leaves into singly compound ones. Of less fundamental importance, 
perhaps, is the disappearance of starch and the formation of 
cork on leaf organs and young stems. RICHTER (37) has lately 
