O YMNOSPERM^. 



395 



283. A sta- 



t he flower 



tain cells. Each pollen grain is at first a single cell, but by 

 the time it escapes from the anther it is a several-celled body, 

 by the formation of partitions within its cav- 

 ity (q, y, Fig. 281, B}. The daughter-cells 

 thus formed are doubtless the homologues of 

 the prothallium of the higher Pteridophytes. 

 Each mature grain has a double wall, of 

 which the outer one (the extine) is hard 



and thick, while 



the inner one (in- 



tint>\ i<3 thin nnrl ' Pinus sylvestris, 



line l ] * showing the two pol- 



delicate (e and /, leneacs. Magnified 



v ' From LeMaout and 



Fig. 281, B). In Decaisne. 



this case (as indeed is common) 

 there are two vesicular protru- 

 sions of the extine (bl, Fig. 281, 

 B), which give the grain the ap- 

 pearance externally of being three- 

 celled. 



The male flowers of Finns syl- 

 vestris are collected into catkins 

 . or spikes (Fig. 282). They are 



'&. n. **., male flower of \ o / J 



eus baccata; a, the pollen structurally similar to those de- 



s. B, a stamen, seen from * . 



below, c, a piece of a foliage- scribed above. The stamens are 



shoot, z. with a leaf, b. in whose , -, , , -, , , 



axil is a scaly axis (the fe- short and broad, and each bears on 



male flower), which is terminated , i i e i. i 



by an ovule, *k ; , the pcnies. its back or outer surface two elon- 



D, longitudinal section of the fe- ~ a i. J nnllon oana fTTirr 9ft^ 

 male tf.wer in C, more magnified; gated pollen SaCS (X Ig. Ab6). 

 i, integument or coat of ovule; 1w ^ll or . o-riiina nrp aimilir tr* 



tt, the body or "nucleus" of the P oll en grams are similar 



ovule ; m, aril ; x, a rudimentary Q^ Abies. 



axillary ovule. (^~ By an error 



of the tngraver the hair line from In TdXUS bttCCttta the male flower 



x is carried about 1 mm. too high .. . .. 



in the figure.) E, longitudinal differs from those described above 



section or an older ovule, but , ,-, , ,-, 



before fertilization ; i, integu- only in the shape or the stamens, 

 S^^i? e *lg a 'tSS which are peltate and lobed (Fig. 

 ft!! 284 ^ B )' The y bear attached to 



to eight 



The 



aril between 1 the' upper --cale pollen-SllCS, which COntaill many 



leaves and the ovule. All the x ' 



figures magnified. After Sachs. globose pollen grains. 



These examples will serve to illustrate the general struc- 

 ture of the male flower, which, with minor variations, 



