

I' 



110 MISSOURI BOTANICAL GARDEN. 



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characterized by scattered tannin cells. Below the insertion of 

 the funicle, there are two longitudinal grooves, one on each 

 side of the ovule, which may be called sutural sulci. These 

 arise as the continuations of the stylar canal, and are earlier 

 functional as pollen-tube guiding grooves already described. 

 Above the funicle the sulci unite and have a common meatus, 

 finally becoming single. The epidermal (endocarp) lin- 

 ing of the sulcus has the appearance of glandular tissue, and 

 simulates the nectar grooves found in certain plants (e. g., 

 Liliaceae). There is a greater amount of tannin in them, 

 in common with the tissues of the placental region than 

 elsewhere in the endocarp. There is, however, no indica- 

 tion of glandular activity. The sulci, as a result of growth 

 pressures, are secondarily more or less irregular in their dis- 

 position, as is seen from the examination of a series of 

 sections. 



Raphide cells are now relatively much less numerous, 

 though they occur in scattered positions throughout the 

 mesocarp. 



The endocarpal epidermis is so far differentiated that the 

 cells are considerably elongated and irregular in tangential 

 contour. 



Seed (f. 7). The torsion begun during the first week 

 (f. 5) has progressed so far that the embryo is now one- 

 third of the entire length of the ovule distant from the orig- 

 inal position. A corresponding amount of torsion has been 

 experienced by the upper end of the ovule, so that the back- 

 ward extension of the endosperm, beyond the chalaza, is 

 well started. The endosperm is parietal, and of a single 

 layer of cells. The tanniferous tissue about the chalaza is 

 very pronounced but is not readily distinguishable on account 

 of the general tnnnin reaction. The chalazal cul-de-sac has 

 enlarged, and continues to do so beyond this period, so that 

 in the definitive seed its size is marked. 



The torsion which the integuments undergo is a differen- 

 tial one. The epidermal colls move relatively less, while the 

 greatest movement is found in the innermost layer of cells. 

 Thus it happens that the exostome of the micropyle does not 



