Photographs enlarged from portions of a motion
photomicrograph, showing the method of cell wall penetration by Pythiumhyphae.
A. — Shows hypha growing toward the
potatocell wall.
B. — Shows hypha attached to wall and about to penetrate.
C. — The tip has just broken through the wall.
D. — The penetration is complete. Note the black line at the point where the hypha penetrates the wall. This may be due to a rolling up of the potato cell wall about the hypha or to a difference in refraction caused by compression of the wall.