VEGETATIVE HEP ROD VCTION. 



251 



the sporangia burst, or are moist and slirl<y, adliering to 



each other in larger or smaller 



clusters (fig. 264). Sometimes, 



as in orchids and nn'lkweeds, they 



are all held together in one mass 



by the remnants of the mother 



cells in which they were formed, 



and are attached to a part of the 



tissue of the anther which carries 



the massas a stalk or handle ffigs. 



272,273). Dry spores are usually j,,,, ,^^ _ ^,,,„^^ ^^^^^^^^ ^^ ^,, 



adapted to distribution by w,nd ; TS^i^^,S^:'^^::i ^. 



while the adherent spores are ?<=',= ™''h bases united and only the 



1 .. Ill V. styles distinct, Compafe witli figs. 



adapted to carriage by small ani- ^f'After'Frank^""''''' '''^'"'"' ' '"""' 

 mals, especially insects. (See further ^[ 481.) 



352. Germination in place. — By the time the sporangia 



Fig. 271. — Pollen grains. A, white water lily {A'yin^hfen n/da), B, athistle {Cirsiuiu 

 nentornle). C,z mallow ^Hibiscus ternains). IJ, dandelion {Ta-J'axacuin offi- 

 ciitale). Magnilied 200 diam. — After Kerner. £", pine, showing bladderj' enlarge- 

 ments, [', h, of the outer layer of the cell-wall. The central portion is the body of the 

 spore filled with protoplasm with a large nucleus. From it is separated a leiiticular 

 cell,/, the rudiment of the gametophyte. Magnified 400 diam. — .After Strasburger. 



are old enough to release the sjjores, the latter ha\e already 

 germinated and begun to form a new sexual pjlant, the male 

 gametophyte. Thus the spores of the non-se.Kual plant give 



