148 



BOTAXY 



PART II 



segment arising near the upper end of the leaf-stalk. Tliis fertile segment in 

 02)hio(jhissum is simple and cylindrical, with the sporangia sunk in two rows ; in 

 Bolrijchhim it is pinnately branched in the upper part, and tliickly beset on the 

 inner side with large nearly spherical sporangia. 



Our knowledge of the peculiar monoecious protlialli of the Ophioglossaceae is 

 largely due to Biiuchmann ; they are long-lived, suliterranean, saprophytic, 



> 





an 



-r i — o r 



) 



A B G 



Fio. 392.—^, Boiryckiiim hniaria. Spnropliyte. (h nat. size.) iJ, Ophioglosstrm nihjatum. Siioro- 

 phyte showing the bud for the .succeeding year, (h nat. size.) C, Ophioijloxsum ntlgntum. 

 Prothalhis. an, antheridia ; ar, archegonia ; /.-, young plant with the first root ; ad, ad- 

 ventitious branch ; h, fungal liyphae. (x 15 ; alter Bruchm.\nx.) 



tuberous bodies without chlorophyll but inhabited by a mycorhizal fungus. In 

 Oiihioglossum, (Fig. 392, C) they are cylindrical and radially symmetrical, simple 

 or branched ; in Botrycldum they are oval or heart-shaped and dorsiventral. 

 Tlje antheridia (Fig. 39-3) and archegonia (Fig. 394) are sunk in the tissue of 

 tlie prothallus. The antlieridium encloses a large spherical mass of spermatozoid 

 mother-cells which are set free when mature by the swelling of the contents and 

 tlie breaking down of one of the central cells of the wall. Tlie sperraatozoids have 

 a spirally wound body and numerous cilia ; a small vesicle is adherent to the 

 spermatozoid (Fig. 393, E). The antheridia originate from single superficial cells 



