OF BUCKLEYA QUADRIALA, E. ET H. lô 



nutrient substance between the host and the parasite must be to 

 a certain degree impeded. 



Next let us consider the axial part of the haustorium. The 

 axial part is that portion, which is composed mainly of vessels 

 united into two strands with the parenchyma between them. 1 ' If 

 we make a cross-section through the median region of the haus- 

 torium we will find a pair of semilunar vascular strands facing 

 each other and running in the direction of the axis of the host 

 (Fig. 8 va). The central parenchyma, which I propose to eall 

 by the name of />ith, is composed of small polygonal or slightly 

 elongated cells with large nuclei and rich plasm, almost all being 

 of equal size. The pith after passing through certain places of 

 the vascular strands goes up gradually into the cortex, there being 

 no sharp line of demarkation between them (Fig. 8). 2) 



In the strands w T e find also a few parenchymatous cells which 

 are found irregularly scattered in the inner portion, while in the 

 peripheral portion they constitute somewhat regular rows. The 

 characters and functions of these cells will be discussed later on. 



The longitudinal section of the axial part is similar in its 

 form to a flask with rounded base and wide mouth opened at 

 the apex of the haustorium, the strands then corresponding, as 

 it were, to the sides of the flask, and the pith to its contents 

 (Fig. 7 ax). The vessels are generally reticulated, rarely pitted. 

 At the bottom of the flask as well as on the inner surface of 

 its sides, the form and arrangement of the vessels appear very 



1). The reader is requested to notice that the designation of this part of the haustoria 

 ui' Santalacere as given by previous authors is such as to iuclude the innermost tissue of my 

 cortical part with their inner part of the haustoria, which is called by Pitka " Mittere Theil " 

 (lue. cit. ]>. 14) and by SOLMS-LAUBACH ''Kern'' doc. cit. p. 543). 



2). 1'i'iRA considered, in Thesium, the parenchyma between the two strands to be of the 

 same nature as that which surrounds strands, and so he called them " Cambialgewebe." 

 loc. cit. p. 11. 



