396 



INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



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Fig. 211. Sections of ovules of ,$w Datura stramonium from unpollinated ovaries 

 injected with 0.1 per cent naphthaleneacetic acid. A, l.s. ovule 10 days after 

 treatment, note prominent integumentary tapetum. B, l.s. ovule of same age, 

 showing proliferation of cells of integumentary tapetum. C, l.s. ovule 15 days after 

 treatment; note groups of cells occupying cavity of embryo sac. D, l.s. ovule 21 

 days after treatment, showing "pseudoembryo" in embryo sac surrounded by 

 degenerating cells of integument. (After Van Overbeek, Conklin and Blakeslee, 

 1941.) 



