654 MINNESOTA BOTANICAL STUDIES. 



DESCRIPTION of PLATE XLVIII. 



Figure i. Longitudinal section of ovule containing young embryo 

 and endosperm (X5o). The nucellar tissue about the middle of the 

 embryo-sac has broken down. The antipodal body is seen at the 

 lower end of the sac. 



2. Antipodal body (xi6o). 



3. Eight-celled embryo ( x 770). (Outlined with camera lucida.) 

 a = disorganizing synei'gid. 



4. 5, 6. Longitudinal sections of ovules containing spherical embryos 

 and endosperm ( x 240) . 



7. Cross section of ovule containing a spherical embryo closely sur- 

 rounded by endosperm ( x 240) . 



8. Front view of an embryo at end of stage B. a= plumule, bb-= 

 cotyledon. This figure was reconstructed from careful micrometer 

 measurements of serial cross sections ; a proceeding found necessary 

 in order to get the correct orientation of the embryo. 



9. Front view of an embryo at end of stage C. # = plumule. bb 

 = cotyledonary lobe. Figure obtained in same manner as Fig. 8. 



10. Longitudinal section of an embryo in Stage C (X5o). The 

 endosperm is shrunken by reagents into the center of the ovular 

 cavity. 



11. A fruit with one side of the pericarp and a cotyledonary lobe 

 cutaway (X2). #=thicker portion of the testa. 3=common base 

 of the cotyledonary lobes. 



PLATE XLIX. 



12. Cross section of the hypocotyl of an embryo just completing 

 Stage C ( X 50) . 



13. Cross section of the same embryo through base of plumule 



(xso). 



14. Cross section of the same embryo through apex of plumule 

 ^450). a=apex of stem. 6=first leaf. <?=endosperm. 



15. Cross section of an embryo, cutting plumule a short distance 

 above its base ( x 50). e endosperm. 



1 6. Cross section of same embryo through cotyledonary lobes 

 (X5o). e=endosperm. 



17. Longitudinal section of an embryo early in stage D (x65). 

 The fundament of the first leaf is already evident, also the invagi- 



nation at the base of the embryo, which marks the position of the 

 radicle. 



