196 
The oxygen percentage in the cocoon is always lower than in 
the corresponding intercellular spaces. 
The oxygen percentage in the intercellular spaces of the roots 
and rhizomes of the aquatic plants from which the larva as 
well as the pupa gets its air is low, seldom higher than 
10 %/o, and can. decrease to a few percent, during winter even 
below one percent. ; 
But oxygen has always been found. 
5,—2.—1915. 
