OF BUCKLEYA QUADRIALA, B. ET H. 25 



3). They store up starch during the resting season in the 

 same way as other parenchymatous cells. 



4). The apical cell of the cortical part does not differ at 

 all from that of the axial part, both being nucleated and rich in 

 plasm (Fig. 11). 



These facts led me to conclude that no elements for the 

 translocation of the plastic substances, at least in the form of 

 sieve-tubes, exist in the cortical part of the haustorium of 

 Buchleya. 



4. The Medullary Rays. 



So far as I know, we are not yet aware that medullary rays 

 occur in the haustorium of any parasite. In Buchleya, in which 

 the vascular strands grow to a considerable thickness, the de- 

 velopment of such tissue is to be expected, when we consider its 

 physiological importance in stems and roots. It originates very 

 early, when the vessel begins to be differentiated from among 

 the procambial cells. Then we notice that some cells retain their 

 parenchymatous nature, while others develop into vessels ; but 

 since the arrangement of the former at this early stage is very 

 irregular, it can not yet be decided whether they have the 

 property to differentiate into medullary rays or not (Fig. 14). 

 {Cf. p. 13). Indeed Solms-Laubach 11 ol »served also parenchym- 

 atous cells in the vascular strand of Then tun, but about these 

 he recorded merely that they are of the same kind as those of 

 the cortex bordering the axial part. It is only after the full 

 development of vessels, that the arrangement of these cells into 

 definite medullary rays, which pass through the vascular strands 



1). loc. cit. p. 544. 



