[Vol. 10 



374 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Materials 



Solution 1 Time 



Wash 



Flu 



Chromo-acetic (0.5 gm. chromic 



acid 

 1 .0 cc. glacial acetic 

 100 cc. H,0) 



12 hr. 



12 hr. running HiO 



Flax 



Sweet-potato 



Horseradish 



Parsnip 



Corrosive sublimate + acetic 



acid 



(1.2 g. Hublimate 



3 . cc. glacial acetic 



100 cc. alcohol of, 



(a) 5% or 



(b) 15% or 



(c) 95%) 



3-4 hr. 



12 hr., 



(a) 5% alcohol 

 or (b) 15% alcohol 

 or (c) 95% alcohol 



The plates, with the exception of pi. 15, illustrate the histological 

 study. Plate 15 shows: (1) a normal flax seedling, one with de- 

 capitated roots, and one with the cut-off cotyledons, with the 

 regenerated shoots and roots as a result of decapitation; (2) the 

 notches of Bryophyllum leaf were the places at which occurred 

 regeneration; (3) a sweet-potato developed roots from the 

 cambium on the cut surface and normally through the cortex 

 and epidermis; (4) the horseradish exhibited a similar condition 

 to the potato. 



Plate 16 shows : (1) a cross-section of a flax stem with the central 

 cylinder of phloem and xylem cells but no well-defined cambium 

 tissue, the large irregular cortex cells, and the small, more regular 

 epidermal cells; (2) b represents the earliest stages in the division 

 of the epidermal cells to form a swelling ; c, d, and e show the con- 

 tinued divisions to form a larger swelling, which finally would 

 result in the formation of a true bud which would then seek 

 direct connection with the central cylinder of the stem. Thus, 

 the origin of the regenerated shoot in the flax is from the division 

 of the epidermal cells followed by the division of the cells thus 

 formed. There is the possibility that if there were a definite 

 cambium that regeneration would originate from those cells, 

 as in the radish, parsnip, etc., when the cambium is present and, 

 undoubtedly give rise to the regenerated parts. 



Plate 17 shows the regenerated root of the horseradish and the 

 regenerated bud of the sweet-potato. Because the sections of 

 both the potato and radish exhibited similar regenerative phe- 

 nomena, only one case from each has been drawn : a shows a well- 



