108 



PLATE XVI. Marchantia polymorpha. 1, Branching shoot 

 with receptacles in various stages of development ( x 15) ; 



2, Section of a young receptacle with underlying thallus ( x 270) ; 



3, Ripe gemma; 4, Embryo plant from a ripe gemma ( x 150). 

 PLATE XVII. Marchantia. 1, Part of a thallus with arche- 



gonia ( x 14) ; 2, Somewhat older portion ( x 8'5) ; 3, Section 

 through two fully-developed archegouia ( x 1620) ; 4, Portion of 

 thallus with antheridia and gemmse-cup ( x 8*5) ; 5, Section of 

 male organs, showing antheridia ( x 45) ; 6, Part of the above 

 section more enlarged ( x 400) ; 7, Mature female disc with 

 sporogonia ( x 9) ; 8, Ripe sporogonium ( x 63) ; 9, Ripe spores 

 with elaters ( x 576). 



PLATE XVIII. Polytrichum gracile. 1, Male and female 

 plants and sporogonium ( x 9*5) ; 2, Longitudinal section of nearly 

 ripe theca ( x 100) ; 3, Ripe theca after removal of the oper- 

 culum ( x 38) ; 4, Operculum of theca ( x 38) ; 5, Ripe spore in 

 section ( x 3100) ; 6, Ripe spore crushed ( x 3100) ; 7, Transverse 

 section of a ripe theca ( x 100) ; 8, Two germinating spores 

 (x 3000). 



PLATE XIX. Aspidium Filix-mas. 1, Transverse section of 

 a fertile pinnule ( x 350) ; 2, Closed ripe sporangium ( x 750) ; 



3, Burst sporangium ( x 750) ; 4, Two ripe spores ( x 2500) ; 

 5, Under surface of fertile pinnule ( x 23). 



PLATE XX. Aspidium Filix-mas. (Prothallium). 1, Ger- 

 minating spore 25 days old ( x 1400); 2, Further developed 

 protonema (x 1400); 3, Protonema two months and seven 

 days old ( x 450) ; 4, Prothallium of A. violascens seen from 

 below, with reproductive organs ( x 140) ; 5, Prothallium of 

 A. violascens with young fern ( x 25). 



PLATE XXI. Equisetum Telmateia. 1, Development of the 

 aerial shoot ( x 2) ; 2, Transverse sections of the ripe spike 

 (x 18); 3, Fertile leaf from within (x 80); 4, 5, Ripe spores 

 ( x 1500) ; 6, Ban-en shoot ( x 2). 



PLATE XXII. Selaginella helvetica. 1, Reproductive plant 

 (x 23); 2, Longitudinal section of a fertile spike (x 132); 3, 

 Young sporangium with spore mother-cells ( x 1050) ; 4, Tetra- 

 hedral division of a spore mother-cell ( x 5200) ; 5, Ripe micro- 

 spore ( x 352) ; 6, Four .ripe microspores ( x 1750) ; 7, Leaf 

 with ripe microsporangium ( x 132). 



PLATE XXIII. Cycas circinalis and C. revoluta. 1, Female 

 plant of C. circinalis ( x J) ; 2, Young carpellary leaf ( x 1) ; 3, 

 Older carpellary leaf ( x 2) ; 4, Fully-developed carpellary leaf 

 of C. revoluta ( x 3). 



PLATE XXIV. Taxus baccata. 1 , Branch with flowers ( x 5) ; 

 2, Section of a flower ( x 50) ; 3, Branch with ripe seeds ( x 1) ; 



4, The same (x 8); 5, a, b, Ripe seed (x 10) ; 6, Section of a 

 ripe seed ( x 120) ; 7, a, b, Germinating seed in section (x 7); 

 8, Young plant with cotyledons ( x 2). 



