THE ARCHEGONIAT^ 



217 



are composed of almost perfectly uniform, green parenchyma, and no 

 trace of a midrib 

 is ever found in 

 the leaves. 



The lower lobe 

 of the dorsal 

 leaves, especially 

 in many of the 

 epiphytic tropical 

 species of Lejeu- 

 nia, becomes folded 

 over so as to form 

 a little sac (Fig. 

 181), which is ap- 

 parently useful in 

 storing water. It 

 is said that in some 

 instances these 

 sacs serve to en- 

 trap small crusta- 

 ceans or insects, 

 acting like the 

 traps found upon 

 the leaves of Utri- 

 cularia. 



FIG. 177. Madotheca Bolanderi. Successive stages in the 

 development of the young antheridium, longitudinal sec- 

 tions (X 600). 



Branching. The branching in the Acrogynse is always monopodial. The 

 lateral branch replaces the lower lobe of a leaf. In the ventral half of the 



FIG. 178. Madotheca Bolanderi. Development of the embryo. A-D, longitudinal 

 sections. E-G, series of transverse sections of an embryo. B and Care successive 

 longitudinal sections of the same embryo (X 525). 



