OIL-RESERVOIRS 



527 



Berthold's statements. In thin transverse sections of the rhizome of 

 Asarum europaeum, which have been treated with alcohol in order to 

 remove the ethereal oil, the strongly cutinised cup-shaped stalk can be 

 readily distinguished under a sufficiently high magnification ; it is 

 seen, on the one hand, to be continuous with the suberin-lamella of the 

 cell- wall, while in the other direction it is prolonged into the extremely 

 delicate vesicle which envelopes the oil-drop (Fig. 2 1 3 b). In alcohol 



)D@raQC 



Fio. 213. 



A and B. Oil-reservoirs of Asarum europaeum ; A, from a scale-leaf (surface view) ; 

 B, from the ground-tissue of the rhizome (T.S.). ft T.S. through a leaf of Laurus 

 nooilis, showing an oil-reservoir. (Oil removed by treatment with alcohol in ever}' 

 case.) 



material the vesicle is collapsed and wrinkled, and appears to be 

 covered with minute granules. In order to obtain a surface view, it 

 is best to examine the outer (adaxial) epidermis of the scale leaves (of 

 the rhizome) which contains numerous oil-cells (Fig. 213 a). The 

 cup-shaped stalk of the vesicle will then be seen, in every case, to be 

 attached near the centre of the outer wall of an epidermal cell ; the 

 cavity of the stalk presents the appearance of a sharply defined circle, 

 not unlike a minute pit, surrounded by a circular border, which corre- 

 sponds to the wall of the cup. From the outer edge of this border 

 there frequently arise numerous radiating striae ; these correspond to 

 the wrinkles which, as already stated, are produced in the wall of the 

 vesicle, when the oil is removed with alcohol. The oil-cells in the 



