eS —— _ — 
The influence of carbon monoxide and other gases upon plants 
H. M. RicHarps anp D. T. MacDoucat 
A CORRECTION 
By reason of direct misinformation imparted by the Chemiker- 
Kalender of R. Biedermann (pages 348-349 in the 1904 edition), 
it is necessary to introduce a correction in the estimates of the 
CO content of the illuminating gas mixtures used in the experi- 
ments described under the above title in the February issue of 
the Bulletin of the Torrey Botanical Club. It is categorically 
stated in the above-mentioned Chemiker-Kalender that ethylene 
and the two higher hydrocarbons of the same series (all of which 
may be present in considerable quantities in illuminating gas) are 
wot absorbed by an ammoniacal solution of cuprous chloride. 
Such, however, has been since found to be incorrect ; these hydro- 
carbons may be so absorbed, at least as far as the first named is 
concerned, 
Consequently the approximate CO content of the gas in ques- 
tion is uncertain, but was probably nearer 25 per cent., and there- 
fore on page 58, line 14, and page 66, line 20, Vol. 31, of the 
Bulletin of the Torrey Botanical Club, the numeral 40 should be 
striken out and the numeral 25 substituted. 
This does not invalidate, but rather strengthens the conclusion 
that the greater toxic effect of illuminating gas over CO alone, on 
the plants experimented with, is due to other gases than the CO 
itself, 
