110 MANUAL OF BOTANY 



develop the capsule. All the cells of the endothecium go to 

 form the archesporium, which gives rise to the spore mother 

 cells and to the elaters. The latter are very hygroscopic, and 

 assist in the disseminating of the spores when the capsule 

 opens. When mature, the capsule is forced out of the calyptra 

 by the elongation of a short seta, or stalk, developed from the 

 hypobasal region by intercalary growth. It then opens longi- 

 tudinally by a number of fissures, and the spores are liberated. 



Other members of the thallose group show certain differ- 

 ences from Marchantia. In the lower forms the sexual organs 

 are not borne upon special gametophores, but arise from the 

 ordinary dorsal surface of the thallus. In some the plants are 

 not dioecious, the same thallus producing both antheridia 

 and archegonia ; in some Eiccias both organs occur together in 

 the same sorus. 



In Anthoceros and Blasui, chiefly on the under surface of 

 the shoots, various cavities occur which are filled with mucilage. 

 In these, quantities of the Alga Nostoc live symbiotically. The 

 cavities become irregularly septate in consequence of filamen- 

 tous outgrowths from the cells of their walls. 



Anthoceros is peculiar also in the fact that its chloro- 

 Ijlastids contain pyrenoids like those of the Alg*. 



The sporogonium of Anthoceros is peculiar in two respects. 

 Its endothecium is sterile and forms a columella, while the 

 archesporium is developed from the inner layers of the amphi- 

 thecium. It continues to elongate by basal growth, forming a 

 long pod-like body which dehisces from the apex downwards by 

 two valves. 



FoLiosE Liverworts. — The foliose liverworts have a dorsi- 

 ventral axis bearing leaves which are generally of two kinds. 

 The ventral surface produces a row of very rudimentary ones, 

 which are known as ampliigastria, while on the lateral faces are 

 developed the ordmar^' foliage leaves. Eoot hairs also spring 

 from the ventral side, and mucilaginous secreting hairs occur 

 near the growing point. 



The growth in length is carried out by a single apical cell, 

 which is sometimes two-sided, and hence cuts off two series of 

 segments. In some forms the apical cell is a three-sided pyra- 

 mid. Each segment produces a leaf and also contributes to the 

 increase of size of the stem. The branching of the axis is 

 usually monopodial. 



Vegetative reproduction is carried out by means of gemmae, 

 as in Marchantia, but the gennn* are, as a rule, simpler in 



