350 



BOTANY. 



K 



takes place simply by the decay of the sporogonium ; in 

 Antlioceros the long sporogonium splits 

 vertically into two long valves (Fig. 

 239), while in the greater part of the 

 class it splits regularly 

 into a definite number 

 (four to six) of recurv- 

 ing segments ; in the 

 Fig. 239. Plant of An- latter the elaters, which 



right, sporogonia un- are present, doubtless 



opened; K, on the left, -j opf finer 4- V, p 

 sporogonia opened. After aia 



^ ran "- spores free. The struc- 



ture and development of the elaters are 

 shown in Fi?;. 240. 



The following are the principal orders of the 

 Hepaticse : 



Order B-icciacese. Consisting of terrestrial or 

 aquatic annual plants of small size ; the plant- 

 body is a dichotornously branched thalloid stem, 

 which bears a row of scale-like leaves upon the 

 under side. The sexual organs occur singly on the 

 upper side of the stem, and the sessile, spherical 

 sporogonia (capsules) are immersed in it or sessile 

 upon it ; the capsule breaks irregularly upon the 

 decay of its walls ; and there are neither perianth 

 nor elaters. 



Order Anthoceroteae. Terrestrial annual 

 plants with an irregularly branched thallus. The 

 sexual organs are imbedded in the upper surface 



of the frond, and are of very simple structure : the . Fi ?- 240. Two ela- 



, tere in different stages 



sporogonia are long and narrow, and dehisce by of development. The 



splitting into two valves ; perianth none ; and the one n * he left is seen 



, to be an elongated cell 



elaters, wlien present, imperfect and rudimentary, with no trace as yet 



Order Marchantiacese.- Terrestrial perennial ^ 



. 

 plants, with a thick, creeping, and dichotomously side are several young 



branched stem, furnisl.ed beneath with numerous th^rightT^manire' It 

 scale-like leaves and root-hairs ; above, the stem is is composed of the spi- 

 provided with a well-developed epidermis, and pe- 

 culiar stomata of a complex structure, comnmni- 



tfons oMhe 

 L nte - rv ^ n u n 'I. P rtions 



eating with lozenge-shaped cavities (Figs. 78 and A, A, are*" mature 

 79, pp. 91-2). The sexual organs are developed on fP r s ^E^ 

 special erect branches, and they may occur on the Decaisne. 

 same, or on distinct plants ; the sterile or antheridial branches, which 



