150 



PLANT STEDCTCJRES 



tendency to restrict the sporogenous tissue and increase the 

 sterile tissue. It will be observed that with the introduc- 

 tion of the leafy sporophyte among the Pteridophytes the 

 sporangia appear much later in its development, sometimes 

 not appearing for several years, as though they are of 



■^ _P 







Fin. 1:^1. A series showing the (U-hisccnce of a fern sporangium, the ruptnre of tlie 

 wall, the straightening and bending back of the anniilus, and the reeoil.— After 

 Atkinson. 



secondary importance as compared with chlorophyll worJs ; 

 and that the sporogenous tissue is far more restricted, the 

 sporangia forming a very small part of the bulk of the 

 sporophyte body. 



