300 THE BIOLOGY OF THE PLANT 



of the outer wall. Draw. Crush the wall by- 

 pressing upon the cover-glass and notice the con- 

 tained sacs, the asci. How many does a single 

 sporocarp contain? What is the shape of an 

 ascus? What is its structure? How many spores, 

 the ascospores, does each ascus contain ? What 

 differences can you detect "between these spores 

 and the conidia ? Draw an ascus with its spores. 

 Look for sporocarps in various stages of growth. 

 They develop from two branches which become 

 twisted around each other in the form of a short 

 spiral. Draw all of the stages found. 



PHYSIOLOGY 



a. The germination of the conidia. 



Prepare a moist chamber, using. a drop of Pas- 

 teur's fluid with sugar for the hanging drop. With 

 the fine forceps pick up a few aerial hyphse with 

 conidiophores, and sweep the conidiophores over 

 the surface of a drop of water on a slide so as to 

 brush off some of the conidia into the drop. Then 

 dip the point of a needle first into the drop of water 

 and then into the hanging drop, thus transferring 

 z,few conidia to the latter. Examine the conidia 

 from time to time for three or four days. How 

 long before you can detect signs of germination ? 

 What is the first change noticed? How many 

 hyphse does each spore form? Do these hyphse 

 branch ? Do they interlace to form a mycelium ? 

 Do the mycelial hyphee unite ? 

 Draw the various stages of germination. 



General Questions. — How do you account for the very 

 wide distribution of blue mould ? For its occurrence in 

 cans of preserves ? 



