46 VEGETABLE HISTOLOGY. 



tie portion of the wall of the spore case remains adhering to 

 the stalk as a collar. The cavity of the stalk does not com- 

 municate with the sporangium, but is cut off by a bulging par- 

 tition, forming a central projection known as the columella. 

 This may be mistaken for the spore case itself. 



The spores arc oval and larger than those of Penicillium, 

 consisting of a sac enclosing protoplasm and a nucleus. When 

 sown in a proper medium they send out hyphoe and produce a 

 new plant. The spores are at first colorless, but when ripe are 

 colored and give the black appearance to the sporangia. 



The hyphae are cylindrical threads, longer and larger in 

 diameter than those of Penicillium, and when young have no 

 dividing partitions, so that each hypha, however long, with 

 all its branches, forms a single cell. In old growths, partitions 

 may be found after the production of sporangia. The hyphae 

 contain granular protoplasm with vacuoles and nuclei. 



Carefully remove some hyphae, white (unripe) and dark 

 spore cases with a teasing needle or forceps to a slide and keep 

 them spread apart. Add a drop or two of 70 or 80 per cent, 

 alcohol and cover. Water causes the spore cases to swell and 

 burst, hence should not be used. Examine with low and high 

 power. Note the hyphae, spore cases (both whole and broken), 

 columella, spores, protoplasm, etc. Also apply fuchsin and 

 iodine stains and note the effects. Compare with Penicillium 

 as to its dimensions of parts. 



When moist bread is allowed to become mouldy Mucor is 

 apt to be the first growth. Later on this mould will die away 



Fig. 31. Mucor stolonifer. a, hypha ; b, ripe spore case ; c, collar or remains of 

 broken wall of spore case ; d, columella or dome-like partition separating spore 

 case from the cavity of its stalk, g ; f, broken spore case with spores ; e, young 

 spore case, spores not yet formed ; h, spores. 



and Penicillium or Eurotium will get the upper hand and flour- 

 ish. The source of the mould is the spores which float about 

 in the air or are present in water. 



CLAVICEPS PURPUREA (ERGOT OF RYE). 



Claviceps is a genus of the fungi whose different species pro- 

 duce Ergot grains on various kinds of grasses. The hyphae of 

 the species Claviceps purpurea begin their development on the 



