2276 Journal of Applied Microscopy 



3. Compare the size of a yeast cell with one of the bacteria present. 



4. Stain with iodin solution. Notice, the yellowish-brown color of the yeast 

 plants and the blue of the large starch grains of the yeast cake. Is there any 

 starch in the yeast cells ? 



5. Draw a large cell carefully, showing granules in the protoplasm and one 

 or more large vacuoles. 



6. Note. Yeast plants produce alcoholic fermentation in saccharine solu- 

 tions. Dry bread yeast is usually a form of the beer yeast, and is known as 

 " surface yeast." 



XXX [I. Morchella esculenta (L.) Pers. Morel. 

 Class, Ascomycetes. Order, Helvellales. Family, Helvellacea;. 

 This edible morel is common in spring and summer in moist woods and 

 shady hillsides. Specimens may be preserved in 70 per cent, alcohol. 



1. Make a careful sketch of the entire, fleshy, fruiting body, representing 

 the stalk and the deep-pitted pileus on whose surface the asci are borne. 



2. Tease out a piece of the stalk and mount in water. Examine under high 

 power and draw some of the mycelial threads. Note that the entire body is a 

 spurious tissue of interwoven hypha. 



3. Tease out a small piece of the pileus, mount, and study the asci. Draw. 

 How many spores in an ascus ? How do the asci open at the tips ? 



XXXni. Aspergillus herbariorum (Wigg.) Fisch. Common Green 

 Mould. 



Class, Ascomycetes. Order, Aspergillales. Family, Aspergillaceae. 



This mould is exceedingly common on improperly canned fruit, on cheese, 

 and on decaying plants ; especially on plants in press for the herbarium when 

 the driers are not frequently changed. The conidial stage is of a greenish color 

 while the ascosporic stage is of a bright yellow-orange to the naked eye. 



1. Conidial Stage. Mount carefully in water and study under low power. 

 Under high power draw a conidiophore with conidia. Describe. How are the 

 conidia developed ? Draw a piece of the vegetative mycelium, showing the 

 transverse septa. 



2. Ascus Stage. Mount some of the white mycelium around the margin of 

 the yellow centre. Under high power draw one of the peculiar coiled hyphal 

 bodies present. These represent the conjugating branches, from which a fruit- 

 ing body develops. 



3. Draw the mature fruiting body (ascocarp) under high power, from a 

 mount of the yellow colored mycelium. Notice the asci containing ascospores. 



4. Crush the ascocarps under the cover-glass and draw an ascus with spores. 

 Describe the life history of the plant. The ascocarp may be compared in a 

 general way with the cystocarp of Polysiphonia. 



XXXIV. Uncinula salicis (DC.) Wint. 



Class, Ascomycetes. Order, Perisporiales. Family, Erysibaceae. 

 This powdery mildew grows as a parasite on the leaves of various species of 

 willow and can usually be found without difficulty in the autumn. It forms a 



