1908] CROCKER AND KNIGHT—CARNATIONS 263 
entiation of the primary tissue, and in hindering the formation of 
chlorophyll. Gametophytes of certain mosses were found to be 
very resistant, suffering very little injury in high concentrations of 
these gases for three months. A more delicate moss, presumably 
Mnium undulatum, however, showed deleterious effects earlier. In 
Elodea and Nitella older cells were most injured, and the injury was 
shown by plasmolysis of the. cells. A considerable part of their 
experimentation with illuminating gas serves to confirm the results 
obtained by Motiscu, NEtyuBow, Boum, and others. The con- 
clusion that “illuminating gas affords, in addition to the action of 
carbon monoxid, the results of the action of other substances dele- 
terious to plants” seems to indicate that the work of NELJuBow and 
others was entirely overlooked. 
STONE (13) calls attention to the fact that very small leaks (2-3 
per day) of gas may cause local injury to trees. Among manifesta- 
tions of gas-killing in trees, he notes the early appearance of an 
abundant growth of fungi in contrast to the relatively late appearance 
on other dead trees. In speaking of the distance gas may travel he 
says: “In gravelly soils we have known gas to travel 2000 feet 
without difficulty, when the ground is frozen, and escape into the 
cellar of a house ; whereas in heavier soils gas is more likely to be 
restricted to smaller areas.” 
RICHTER (14) and other investigators have pointed out a number 
of effects of impurities of laboratory air upon the responses of seed- 
lings. RIcHTER believes that in a number of cases the negative 
8eotropism of hypocotyls is greatly weakened by these impurities. 
© points out that a one-sided illumination will produce far more 
nearly a horizontal position with than without these impurities. 
He likewise asserts that in many species the degree of horizontality 
from one-sided illumination indicates the degree of impurity of the 
ar. He found great variation, however, in sensitiveness in different 
Species even of the same genus. 
2. Scope, method, and preparation of material 
It is quite commonly asserted that plants do poorly in houses 
ted with gas and especially is the flowering interfered with. 
Various inquiries have come to us from carnation growers as to the 
