FERMENTATION ORGANISMS 109 



sporangiophores 1-5 cm. in height. At first the growth is creamy 

 white ; later, as the sporangia mature, it becomes dark brown or 

 black. The purely vegetative structure, the mycelium, develops 

 mainly in the substratum. 



Mucor is a fungus belonging to the class Phycomycetes, or 

 Alga-like fungi. Mucor mucedo may grow in saccharine solutions 

 and cause therein a weak alcoholic fermentation. 



The salient features of the fungus are brought out by the 

 following outline : 



1. Examine a culture of Mucor and note 



a. The general appearance of the whole mass. 



b. The position and direction of the threads with reference 



to the supporting substratum. 



c. The aerial hypha} (sporangiophores) upon which the 



black tips (sporangia) have formed. 



2. Examine microscopically a bit of agar from a Petri dish 

 inoculated with Mucor at the previous laboratory period. Note 



a. The mycelium, consisting of branched hypha 1 . 



b. The granular protoplasm in the hyplue may be found in 



motion. Is the movement of the protoplasm uni- 

 form ? Is it ever reversed ? Do you find vacuoles 

 present ? Are cross walls present ? Draw a young 

 branched hypha. 



3. In suitable material distinguish upright hypha) which have 

 a swollen tip containing an abundance of granular protoplasm. 

 Is the swollen tip separated from the hypha by a transverse 

 wall ? The tip is the beginning of the sporangium. 



4. In older material distinguish the spores forming in the 

 sporangia. Find also mature sporangia with ripe spores. Note 



a. The sporangium wall. 



b. The ripe spores. 



c. The swollen tip of the sporangiophore (columella). 



5. Draw a young and a mature sporangium. 



6. Sexually formed spores (zygospores) are rarely found in 

 Mucor. For details of the process the student is referred to 

 Campbell's " University Textbook of Botany," page 160. 



