189 
13/7 1914. Analysis of intercellular air from a Nuphar 
root, the plant having been pulled up the 
foregoing day, 18 hours before the ana- 
Freie Was: måde sa SNE ESS 8,4 lo 02. 
Br <—. Analysis of corresponding roots just after 
the plant had been pulled up......... 7-8 "lø Og. 
We can now take for granted that the following analyses are 
in accordance with the real circumstances, disregarding accidental 
errors. In respect to oxygen such errors are negligible (the 
maximum error can on account of the difficulties connected with 
making analyses in the free, in a boat, amount to half a percent). 
With regard to the carbonic dioxide the determinations are not so 
exact. On account of the speedy diffusion of this gas into the 
water the CO, will as a rule be found lower than it is in reality, 
and it will in particular depend on the way in which the airbubble 
for the analysis is procured; if one succeeds in getting it into the 
funnel of the apparatus as a big bubble, the error will be little, 
but if the air is procured in the shape of small airbubbles, which 
especially is the case with small and thin roots, the error can be 
s0 considerable that the CO, determination may become quite 
worthless. 
In the following I shall mention a series of analyses of inter- 
cellular air from roots of different waterplants on which the 
Donacia larva is living. Most of the analyses have been taken 
from places where a larva was situated. 
0 
"13/7 1914. Composition of the- intercellular air in | 10,5 åg 02. 
foote of Nuphar ...... 6,4 "lo 02. 
| 48 he Os. 
26 "le 02 
Only in few analyses from July I have found air so exhausted 
of oxygen as the last mentioned analysis shows, generally the 
oxygen percentage varied between about 6 and 10. 
