Nov. IS . 1920 Crownwart of Alfalfa Caused by Urophlyctis alfalfae 305 



assimilation is made possible by the zone of haustorial processes, each 

 of which has in a manner similar to the apical process become branched 

 to form a ramifying apparatus (PI. 48, A-D, ra, rb). 



DETAILS OF MORPHOLOGY AND CYTOLOGY 



The branched haustorial processes with their unusually definite local- 

 ization, either as a solitary apparatus at the apical end of the vegetative 

 cell or arranged in a well-defined zone between the equator and the dis- 

 til pole of the resting spore, constitute perhaps the most striking mor- 

 phological feature of the parasite. Although the literature regarding 

 these structures, especially with reference to their development and 

 orientation on the resting spore, is unsatisfactory, there seems to be 

 good reason to believe that all the other species usually referred to Uro- 

 phlyctis, as well as many species commonly assigned to related genera, 

 will show complete similarity to U. alfalfae in this respect. Thus De- 

 Bary (3) in his account of Physoderma (Protomyces) menyanthis states 

 that— 



Auf demselben (distil) Ende der Blasen finder man sehr haufig ein Biischelchen 

 sehr feiner und kurzer in ein Kopfchen endigender Faden, welche bald verschwinden 

 und iiber deren Bau und Zweck ich nichts Naheres angeben kann ; 



and in the figure referred to the appendages are clearly represented at 

 the apices of the obovoid vesicles ("verkerteiformige Blasen"). Ludi 

 (15), who later studied the same fungus, figured a number of unbranched 

 processes arising independently but in close proximity to each other 

 from the apex of the "Sammelzelle" ; and in a few cases he represented 

 a hypha arising also independently from the midst of this cluster. Biis- 

 gen (4) observed the same structure in Physoderma (Cladochytrium) 

 butomi at the apex of the swellings less rich in contents. Like DeBary 

 this author remained uncertain as to their function but considered it 

 probable that the apparatus consists of budding hyphae together with 

 granular host protoplasm. He reported, too, the presence in this spec- 

 ies of — 



irregular cylindrical projections which appear early on the spore, and later are not 

 greatly inferior in length to the diameter of the spore. Stained with iodin, a mem- 

 brane and hyaline contents with a few granules may be recognized. When the spore 

 matures, these break down. 



These structures he designated as haustoria and related their function, 

 in our judgement altogether correctly, to the assimilation of food mater- 

 ial. His figures, however, with the exception of figure 19, a, which shows 

 a detached branching rhizoid, lack clearness and lead one to believe that 

 probably groups of newly proliferated young turbinate cells were con- 

 fused with the rhizoids. On the other hand, the haustoria he shows 

 associated with the resting spores of Physoderma {Cladochytrium) flam- 

 mulae suggest a good possibility of a zonate arrangement similar to that 



