CRYPTOGAMS AND PHENOGAMS 551 
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Fic. 378.—Norway Spruce. Ovule cut vertically and enlarged to show the 
embryo-sac (e) filled by the prothallus or endosperm and two archegonia 
(a), each with its neck (c) and swollen part (0) which contains an egg- 
cell with a nucleus (n); the nucellus (nc) surrounded by the integuments 
(7); pollen-grains (p) from which come pollen-tubes (¢) extending to the 
archegonia; and a part of the seed-wing (s). (Strasburger.) 
Pinus and related genera will doubtless be sufficiently clear without 
further explanation, but the carpels and ovules call for more de- 
tailed examination. Each carpel, as we have seen, bears two ovules 
on its upper side near the base (Fig. 258, 8). When cut in half 
vertically such an ovule exhibits the parts shown in Fig. 378. A 
single macrospore organically connected with the surrounding tissue 
constitutes what is termed the embryo-sac (e).. The rest of the ovule 
represents the macrosporangium, which is divided into a central 
part, the nucellus 1 (nc) in which the embryo-sac is embedded, and 
an outer layer, called the integument (7), which covers the nucellus 
except at the micropyle. Microspores, 7. e., pollen grains, intrusted 
to the wind, are carried to the pistillate flowers. Caught by a 
1Nu-cel/lus < L. nucella, a little nut. 
