241 
On dissolving out the pigment with alcohol, the thickenings are 
seen to have a stratified structure (Fig. 1) resembling that of the 
cellulose basis of some cystoliths. They are not, however, composed 
of cellulose, as they do not give a blue colour with iodine and 
sulphuric acid, or with Schulze’s solution. eee ee micro- 
chemical reactions were tried, and the results appear to indicate 
that the thickening-masses consist of some bubsides related to 
mucilage, but of a rather resistant character, and containing a 
slight admixture of protein. 
A periderm is formed rather early in the root, and arises in the 
third os fourth layer below the surface. Between the periderm and 
the endodermis there are usually from four to six pre of cells 
representing the inner portion of the primary cortex. This is the 
region in which the cystolith-like thickenings occur. They are 
present in many of the cells and are generally attached to the 
cell-wall just where it borders on a small intercellular space, and 
thus are often arranged in groups of three or four (Fig. 1), 
The colouring matter in Buttonia may be compared with that found 
in Craterostigma pumilum, another member of the Scrophulariaceae, 
Craterostigma the pigment is red, but is to be classed with 
the xanthic series of compounds, and also has a peculiar mode SS 
occurrence in the root. Here it meee in granular form, and i 
ound in intercellular spaces in the cortex, lyi ng on the darface 
of the cell-walls bounding these spaces.* 
Wa \ 
KG 
ao 
( 
= 
l. 
Fia. 1. Buttonia, thickenings in cortical cells (x 390). 
FiG. 2. Section through haustorium of Buttonia and root of host (x 10). 
The haustorium of Buttonia attacks the root of the sg ge in 
the usual way, and penetrates the vascular cylinder of t atter 
(Fig. 2), aesceally reaching the centre. In some cases ee root of 
* Marshall Ward and Dale, Trans. Linn, Soc., 2 ser., vol. 5, p. 346, 
