46 



Woodheiid: Notes on the Bluebell. 



If transverse sections are made throug-h different regions of 

 the root and compared they help to explain this feature. Sections 

 through three regions of a fresh root are shown in Fig. 5. The 

 first one (Fig. 5, a) shows the cortical region of the, as yet, 

 unwrinkled portion, where we see that the cells are all small and 

 rounded. A section through the middle of the wrinkled portion 

 is seen at b, also Plate III., 5 ; the mid-cortical cells in this 

 case have greatly elongated radially, producing a distortion of 

 the outer cells ; whilst in section c, taken through a part 

 near the bulb, not only have these cells, but the inner ones also, 

 up to the endodermis, undergone radial elongation (Plate 3, 



5» tr;uis\erse sections throug-h cortical regions of contractile root ; a, throug-h uncon- 

 tractcd region ; h. at a hig-her level showings radial elong-atic>n of mid-cortical cells ; c. 

 near bulb, radial elongation complete. X 50. 



Fig. 6). In this region the cells which originally elongated have 

 been in turn compressed and, along with the outer cortical cells, 

 form a much crumpled tissue. 



As Hugo de Vries long ago showed,'-^' this change is brought 

 about in roots by the increasing turgidity of the cortical cells, 

 which in these cases are more extensible transversely than 

 longitudinally. On the other hand, if roots are placed in alcohol, 



Hugo de Vries, Bot. Zeitung-, 1879, p. 650. 



Naturalist, 



