() AUX. 10. — S. KÜSANO : STUDIES ON THE PARASITISM 



however, seems to display a certain unmistakable inequality of 

 degrees, noticeable already at the end of the first growing period : 

 the most vigorous development is undoubtedly attained by seedlings 

 feeding on Abies and Gryptomeria. As the cultivation is yet at 

 its beginning, it is not possible to decide conclusively whether all 

 these hosts are really able to maintain Buckleya for any great 

 length of time. However, from the mode of development of the 

 parasite, both in nature and in my experiments, it seems possible 

 to conclude that Buckleya prefers Abies and Gryptomeria as its 

 host. 



III. DESCRIPTION OF THE HAUSTORIUM. 



If we examine a young Buckleya, one year old, we see that 

 the whole system of the root from the hypocotyl to the line 

 rootlets is provided with numerous small haustoria firmly adhering 

 to the fine rootlets of the host (Fig. 1), but in the older parasite 

 the axial main pail of the root is free from haustoria, while they 

 are present on the lateral roots and mostly on the distal portions. 

 The form and size of the haustorium vary within wide limits. 

 The form seems to depend mainly upon the size of the host and 

 especially upon the stage of development of the haustorium itself. 

 The young haustorium is generally roundish especially when it 

 attacks slender roots ; but that fully grown is elliptical in surface 

 view, the major axis running across the long axis of the host- 

 root (Fig. 3), and dome-shaped in side view (Fig. o. c). Its 

 external form may partly depend upon its internal structure, 

 which in its turn differs according to the age, so that the form 

 had belter be considered in a later chapter which treats of its 

 structure. Its size also depends in a certain degree upon its age, 



