SUGGESTED LABORATORY EXERCISES 429 



differences in media. This ma}^ be illustrated by altering the concentra- 

 tion of one or more components of the medium. It is suggested that this 

 exercise be carried out in Petri dishes, or in flasks if liquid media are used. 

 Media: This exercise may be divided into four parts based upon the 

 variations in media. 



A. Dilutions of the entire medium. Either liquid or agar media may be 

 used. 



24. Basal medium, containing asparagine and 20 g. glucose per liter 



25. Medium 24 diluted to one-half strength 



26. Medium 24 diluted to one-fourth strength 



27. Medium 24 diluted to one-sixteenth strength 



28. Medium 24 diluted to one sixty-fourth strength 



B. Varying concentrations of sugar. Use either liquid or agar media. 

 The same controls as in A may be used, if the same fungi are tested. 



29. Basal medium, with 40 g. glucose 



30. Basal medium, with 10 g. glucose 



31. Basal medium, with 5 g. glucose 



32. Basal medium, with 2 g. glucose 



C. Change in medium during incubation. Use liquid media in flasks 

 (15 ml. in 125-ml. Erlenmeyer flasks, or 25 ml. in 250-ml. flasks). 



33. Basal medium, same as medium 24 above. Inoculate 10 flasks; after growth is 



near maximum (see instructor), separate the flasks into three groups. 

 a. Replace old medium with fresh medium 

 h. Replace medium with sterile distilled water 

 c. Leave as control 



D. Different natural products as media. Use as agar media. 



34. V-8 juice (diluted to one-half strength) 



35. Potato extract (200 g. potatoes per liter) 



36. Malt extract (20 g. per liter) 



37. Stems of bean, pea, etc., in water agar 



Each student should select one fungus for use in this exercise. It is 

 suggested that the fungi used should ordinarily produce considerable 

 mycelium before fruiting. 



Records; Careful notes must be taken regarding time of appearance 

 of fruit bodies and spores. The amount of growth and sporulation may 

 be compared to that on medium 24. Consult the leader or your instruc- 

 tor for further details on recording data. 



List of test fungi: Aspergillus riigidosus, Ceratostomella Jimhriata, 

 Choanephora cucurhitarum, Endothia parasitica, Glomerclla cingulata, 

 Guignardia hidwellii, Helminthosporium victoriae, Melanospora sp., Moni- 

 linia fructicola, N eocosmopara vasinfecta, Phoma betae, Sordaria fimicola, 

 and Sphaeropsis malorum. 



