CARBON MONOXIDE AND OTHER GASES 65 
firmed this and revealed the fact that the chloroplasts had been 
considerably affected. In the control the cells were full of large, 
somewhat elliptical chloroplasts and about 2 per cent. of the cells 
appeared to be dead. In CO the chloroplasts were smaller, with 
considerable spaces between them, and were fewer in number. In 
shape they were usually similar to the normal, though in some 
cases they were curiously elongated. About 20 per cent. of the 
cells seemed to be dead. In gas as many as 33 per cent. of the 
cells were dead and often quite empty, and the chloroplasts were 
much fewer, paler and smaller than in the control, being often 
nearly spherical in shape. Some of the specimens were returned 
to the respective gases in which they had been, some were re- 
turned to the air. After two weeks the specimens returned to the 
air were examined. The cells not actually killed, had in both the 
CO and the gas specimens almost regained their normal appear- 
ance, though still somewhat paler than the normal. In the gas 
Specimen, however, so many of the cells had been killed that the 
older leaves dried up. The growing tips of all appeared fairly 
healthy. The plants returned to the gases were examined after an 
additional five week’s interval and very little difference was seen 
as compared with the condition presented at the first examination. 
Phulotria Canadensis (Elodea Canadensis) was exposed to the 
same conditions, being arranged so that it came in contact with the 
Moist surrounding atmosphere. The leaves showed a somewhat 
similar degeneration, but rather more serious. After eight days 
€xposure an examination of the CO experiment demonstrated that 
while the young leaves were not so much affected as compared with 
the normal, the older leaves were. arsed cells i in the latter had 
their contents | I lyzed or completely d. Inthe spec- 
imens from ne gas more than half of, the eettz were dead and in 
those that were not the chloroplasts were small and pale. The 
Occurrence of large oxalate crystals was common, suggesting a de- 
Tangement of the assimilatory functions. In the control almost 
all of the cells appeared healthy and showed rotation. 
Some specimens of a WVite//a were followed in a control and 
an 80 per cent. CO experiment. The older cells of both were 
attacked by bacteria and killed, but the younger cells remained 
healthy. In the control the typical rotation was observed and 
