1921} HAUPT—REBOULIA : 63 
studied, and a series obtained as illustrated by fig. 6 a-d. Small 
oil globules are very abundant in the apical cell region and occur 
less abundantly in the cells of the older parts of the thallus. The 
Fics. 1, 2.—Fig. 1, apical cell of thallus and young air chambers, X470; fig. 2, 
upper region of thallus showing air chambers and pores, X 250. 
