180 



PLANT MORPHOLOGY 



spermatogenous cells (Fig. 147D, E). Further development of the 

 antheridium corresponds to that of the Marchantiales. The mature 

 antheridium is generally spherical and either long-stalked or short-stalked. 

 In all the Anacrogynae, as previously stated, the formation of archego- 

 nia never involves the apical cell, all of them arising from its segments 

 (Fig. 145.4). The development of the archegonium is essentially like 



D " t ' F 



Fig. 147. Early stages in the development of the antheridium of Pellia epiphylla, X400. 

 A, division of initial into an inner and outer cell; B, division of outer cell into a stalk cell 

 and primary antheridial cell; C, vertical division of antheridial cell; D, appearance of peri- 

 clinal walls; E, cross section of same; F, later stage, showing two primary spermatogenous 

 cells surrounded by sterile jacket, with stalk below. 



that of the Marchantiales and Sphaerocarpales, but the venter is usually 

 more slender and the neck shows but five cells in cross section (Fig. 148). 

 The number of neck canal cells is variable, but is commonly 6 or 8. In 

 such forms as Pallavicinia and Pellia, however, this number may reach 18. 

 The calyptra, developed from the venter of the archegonium, may become 

 massive, as in Riccardia, Metzgeria, and Symphyogyna. In addition to 

 the involucre, a pseudoperianth is formed in Pallavicinia, becoming con- 

 spicuous after fertilization. 



Sporophyte. The sporophyte of the Jungermanniales is more advanced 

 than that of the Marchantiales and Sphaerocarpales in that a greater 

 amount of sterile tissue is formed. Following the first division of the fer- 

 tilized egg, which is transverse, the lower cell often does not contribute to 

 the embryo proper, but forms an appendage to it. This may become 

 haustorial, as in Riccardia. The upper cell undergoes several transverse 



