I. Objectives: To observe the formation of Sphaerobolus stellatus Tode fruiting bodies and the ejection of the glebal mass.

II. Materials:

• Sphaerobolus stellatus Tode (University of Georgia isolate)
• oatmeal agar: steep 30 g oatmeal for 15 min in 1 L steaming distilled water; decant supernate into fresh 1 L flask; add 20 g agar and bring total volume to 1 L with distilled water; autoclave and pour into Petri dishes
• Parafilm
• plastic Petri dishes
• transfer tool
• dissecting microscope
• fixture with 15 W fluorescent bulb
• 2 Liter Erlenmeyer flasks

III. Procedure:

• Inoculate Petri dishes containing oatmeal agar with Sphaerobolus.
• Seal plates with Parafilm and put in the dark.
• After 3 weeks in the dark at room temperature, bring the plates out and place them 20 cm below the 15 W fluorescent fixture.
• Examine 6-10 days following exposure to the fluorescent light.

IV. Results: Within 6-10 days after exposure to light, 1-2 mm-diameter fruiting bodies (Fig. 1) should be observed on the agar surface. These will begin to dehisce at the apex, revealing a black, viscid glebal mass inside. Shortly after the glebal mass is visible, it will probably be violently ejected by the eversion of tissue layers beneath it. Once ejected onto the Petri dish lid (Fig. 2), the glebal masses will remain adherent, particularly after their adhesive has become dry.

V. Cautionary Notes: Observe standard good laboratory practices for handling fungal cultures, acting as if the culture was a known pathogen (for which concept there is no support).

VI. Reference:

Dykstra, M.J. 1982. A cytological examination of Sphaerobolus stellatus fruiting bodies. Mycologia 74:44-53.

• Figure 1: Clusters of fruiting bodies on agar surface. X****
• Figure 2: Glebal masses stuck to the inside of Petri dish lid. X****