i92o] BROW X—STOM ATA • 307 



PLATE XXX 



Fig. 27. — Surface view of papilla with central stoma; X525. 



Fig. 28. — Structure found in cross-section of etiolated shoot arising like 

 papilla, from epidermis, but growing inward; X525. 



Fig. 29. — Mass of decorticated tissue including papilla, drawn from 

 transverse section of etiolated-greened shoot; X525. 



Fig. 30. — Subcortical development of stoma drawn from transverse sec- 

 tion of etiolated shoot: a, future external epidermal wall; X525. 



Fig. 31. — Part of transverse section of etiolated-greened shoot showing 

 stoma not yet connected with air chamber; collapsed cortical cell also appears 



to left; X525. 



Fig. 32. — Part of transverse section through etiolated-greened shoot: 

 stoma lacked auxiliary cells and opened into air chamber of considerable size ; 

 similar simple stomata present in etiolated shoot; X525. 



Fig. 33. — Freakish stoma found in transverse section of etiolated shoot; 



X395. 



