48 



Woodhead : Notes on /he Bluebell. 



examined at short intervals, and this region was found to be 

 gradually extending. In the second week in June it measured 

 1^4 inches, and increased gradually until, on the 14th of July, a 

 large proportion of the examples had a contractile region of 

 exactly three inches. This seemed to be the maximum, and was 

 reached in some cases by the end of June, in the majority by 

 July 7th, and in others a week later. On the 28th of July most 

 of these roots presented a very dilapidated appearance, and were 

 generally in a state of decay (Fig. 4, b). 



On this date a considerable number were dug up apparently 

 devoid of them, but it was noticed that very slight pressure was 

 sufficient to break them off, and also in their decaying state they 

 were so similar in colour to the soil that they were easily over- 

 looked, and great care had to be exercised to extract them whole. 



A longitudinal section through the base of the bulb and 

 upper region of the contractile root, is shown in Fig. 6, a. At 

 the junction of the two a distinct wavy layer of cells is seen, 

 with slightly thickened lower and lateral walls, the upper wall 

 being very thin. Some of these cells, more highly magnified, 

 are shown (Fig. 6, b). The thickened walls stain deeply with 

 bismark brown, and the layer stands out sharply and well 

 defined. The cells here undergo division and form an absciss or 

 separation layer, which is completed by the end of June or early 

 in July. In the meantime the nutrient materials are withdrawn, 

 and the root is cut off and decays in the soil, leaving only a 

 \'ellow-brown circular scar resembling a leaf scar (Fig. 4, C. Sc.). 

 A section through one of these root-scars is shown in Fig. 6, c, 

 and a few of the cells enlarged at d. 



The base of the bulb develops more on one side than the 

 otlier, and in time the contractile root is placed laterally. 

 Through this enlarged portion adventitious roots bore their 

 way (Fig. 4, a). A new contractile root is developed each year 

 imtil the requisite depth is attained. In the older, nearly mature 

 bulbs, three or even more such roots may be formed, the longest 

 measured, had a contractile region of three inches, and a terminal 

 region of five inches. 



The contraction of roots was first noticed in 1819 by Titt- 

 mann (usually quoted Fittmann), who mentions it occurring 

 in roots of Aster chinensis, Daiicus earota, and ' most other 

 Dicotyledons.''"" Later by De Vries and Sachs in greater detail ; 

 in Aroids by Irmischt and by others, but except for external 

 appearances figures are not given. 



Tittmann, Botanisch-karpologische Bemerunoen. Flora 1819, Bd. II., 

 P. 651. 



I Irmiscli, Beltr. zur vergl. Morph. 5 Abtli, Halle XIIL, 2, 1S74, p. 161. 



{To he continued.) Naturalist, 



