118 



PLANT STRUCTURES 



special development has been in connection with the 

 sporogonium (Figs. 93, 101). 



This complex sporogonium (sporophyte) has a large 

 bulbous foot imbedded in the simple thallus, while 

 above there arises a long pod-like capsule. The com- 

 plex walls of this cap- 

 sule contain chlorophyll 

 and air pores, so that 

 the sporogonium is or- 

 ganized for chlorophyll 

 work. If it could send 

 absorbing roots into the 

 soil, this sporophyte 

 could live independent 

 of the gametophyte. In 

 opening to discharge 

 spores the pod-like cap- 

 sule splits down into 

 two valves. 



Another peculiarity 

 of the Anthoceros forms 

 is in connection with 

 the antheridia and arch- 

 egonia. These organs, 

 instead of growing out 

 free from the body of the 

 thallus, as in other Liv- 

 erworts, are imbedded in 

 it. The significance of 

 this peculiarity lies in 

 the fact that it is a char- 

 acter which belongs to 

 the Pteridophytes. 



The chief direction of development of the three liv- 

 erwort lines may be summed up briefly as follows : The 

 Marchantia line has differentiated the structure of the 



FIG. 101. Anthoceros gracilis : Z, several 

 gametophytes, on which sporogonia have 

 developed ; B, an enlarged sporogonium, 

 showing its elongated character and de- 

 hiscence by two valves leaving exposed 

 the slender columella on the surface of 

 which are the spores; 0, D, E, F, ela- 

 ters of various forms ; G, spores. After 



SCHIFFNER. 



