EXOASCACEAE 135 



before packing, for if sweating occurs the smallest trace of 

 disease will spread rapidly. 



Bulbs should not be planted where the disease existed the 

 previous season, unless the land has been sterilised. 



Massee, Kezv Bulletin, p. 87 (1897). 



Rhizopus nigricans (Ehr.) is also said to attack bulbs at 

 times, although usually a saprophyte. It has also been 

 stated to cause a soft rot of sweet potatoes in the United 

 States. Forming thin, effused tufts which are whitish at 

 first then blackish olive. 



Sporangiophores in clusters, erect, aseptate, springing 

 from long, creeping stolons, rhizoids numerous at the points 

 from which sporangiophores spring. Sporangia globose, 

 blackish-olive, granular, columella hemispherical, spores 

 grey, subglobose, or elliptical, n-14 \i. Zygospore 150-200 /x, 

 wall brown, with rounded warts. 



Halsted, New Jersey Agric. Coll. Expt. Station, Bull. 

 No. 76. 



ASCOMYCETES 



The one constant feature of the members constituting the 

 present group is the production of the spores in specialised 

 cells or asci. The most frequent number of spores contained 

 in an ascus is eight. 



EXOASCACEAE 



This is structurally the most primitive of families included 

 in the Ascomycetes, and in this respect is analogous with the 

 family Exobasidiaceae amongst the Basidiomycetes. In some 

 species the mycelium is only present between the cuticle 

 and epidermis of the leaf or fruit upon which it is parasitic. 

 In other species the mycelium penetrates deeper into the 

 tissues, but is always intracellular, haustoria never penetrating 

 the cells. In all instances the mycelium accumulates between 

 the cuticle and the epidermis, and there produces numerous 

 asci, which rupture the cuticle and develop on the surface of 

 the host. These asci are not enclosed in a receptacle of 

 any kind whatever, but are fully exposed to the air. They 

 are usually densely packed side by side like the cells of the 



