PHANEROGAMIA 



481 



D 



FKI. 440. Pinus montawt. A, Longitudinal section of a ripe male flower (x 10). B, Longitudinal 

 section of a single stamen (x 20). C, Transverse section of a stamen (x 27). D, a ripe pollen- 

 grain of r: n an <ilre*tris(x 400). 



: . 441. .-I -A', Pollen-grains (if (iymnospcrms and stages in the development of the iK>llen-tuly 

 A, Pollen-grain of Ginkgo Inlolxi still enclosed in the sporangium (x 360). K, Pollen-grain of 

 l.ni-i i , wropaea germinating on the tip of the niicellus ( x ItiO). '/-A', Pinus ricio (after COULTER 

 and CHAMBERLAIN ; C, D x 300, K x 250), K, tip of a pollen-tulie which has reached the arche- 

 .-"iiiuni. f, Vi-.^etat ivi-. prothallial cell; gp. spermatogeiKius cell, which xi vl 's rise to the 

 aiithei-idial mother-cell (?n) and its sterile sister-cell (.<) ; ;/, the two generative cells derived by 

 the division of the antheridial mother-cell ; /. , nucleus of the pollen-tnhe, which in A" cannot be 

 distinguished with certainty from the nucleus of the disorganised cells. 



2 I 



