OF BUCKLEYA QUADRIALA, E. El H. 35 



band. Judging from the haustoria of Buckley a, I think I may 

 venture to say that some points in the interpretations of the 

 tissues and the comparative studies on the structures of haustoria 

 of different species, made till now by various authors, are more 

 or less imperfect. Our knowledge of the anatomy of Thesium- 

 haustoria we owe especially to Chatin, Pitea and Solms-Laubach. 

 The last author has also studied the haustoria of Osyris and 

 mentions the following characters as distinguishing that genus 

 from Thesiuyn : — 



a). A very small and narrow axial part (Kern). 



b). A sucker which does not differ markedly from the axial 

 part histologically. 



6'). The more extensive growth of the border of the sucker. 



It appears to me that in comparing the structure of the 

 haustoria of various species, the age and the secondary growth in 

 thickness must be considered. In all haustoria it may be con- 

 jectured that the " Kern " or the axial part should be very small 

 in the earlier stages of development. Since, in Buckleya, the 

 thickness and general form of the vascular strand in the youngest 

 haustoria are nearly similar to those of the adult haustoriuin of 

 Thesium, it would not be improper to conclude that in Osyris the 

 comparatively thin vascular strand, as was mentioned by Solms, 

 should be found onlv in a young haustorium. 



As regards the sucker, its existence was ascertained in Rhin- 

 anthaceae, Lathrœa, Santalacese, etc., each having its characteristic 

 structure. In all these eases, the name sucker was given to that 

 portion of the haustorium, which is imbedded in the host. In 

 Santalaceœ it seems that its tissue was distinguished by Solms- 

 Laubach 1 ' from that of the " Kern " by its more elongated cells ; 



1). lue. cit. p. 556. 



