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DISCUSSION 

 /. W. Green, W. J. Nickerson, H. Ducoff, R. D. Preston, ]. D. Bergeron 



Dr. Green (Rutgers University): During the rupture of the cell wall and 

 explosive budding, is the plasma membrane ruptured? In osmotic hemolysis, 

 the rupture of the red cell can be shown bv rapid photography to occur, not 

 explosively, but by slow swelling. 



Dr. Nickerson; Judging from the appearance of the bud-initial, as seen 

 in the dark-field time-lapse photomicrographs, its resemblance to a spherical 

 protoplast— albeit of natural origin— leads me to suspect that the plasma mem- 

 brane is intact. 



Dr. Ducoff (University of Illinois): How rapid is the change from the 

 filamentous to the non-filamentous form? Is there a "breakup" comparable to 

 that seen in induced bacterial filaments? 



Dr. Nickerson: I have never observed a "breakup" in the filamentous 

 veast comparable to that which we have studied in bacterial filaments. Under 

 appropriate conditions, an inoculum of filamentous cells of a divisionless strain 

 is "diluted out" by budding, to give a population of largely normal yeast cells. 

 These revert to their filamentous phenotype when the condition promoting 

 cellular division is removed. 



Dr. Preston (University of Leeds): How sure are you that the hole asso- 

 ciated with a bud scar is actually blown out? In the algae we are studying, 

 the production of zoospores is followed by the production of a hole in the wall 

 of the parent cell. Stripping through the wall, and electron microscope exami- 

 nation, suggest that these holes are made by progressive dissolution of the wall; 

 only the last few lamellae are blown out by. turgor pressure. 



Dr. Nickerson: Our use of the term "explosive blowout" to describe the 

 budding of yeast is based on two independent observations. First, the lapse 

 of time between consecutive frames showing an intact wall in one and a cell 

 with an extruded bud-initial in the second, is 30 seconds. Second, the orienta- 

 tion of fibrils in the wall components at the site of budding can only be 



