Go 2 Note. 
cell-wall and the formation of a completely new membrane about the escaped 
protoplast. 
Flexion ofihe hypha . When a hypha is acutely flexed the bending almost always 
occurs in the middle region of a cell. If the angle formed be less than forty-five 
degrees the cell-contents tend to separate into two portions, each of which rounds off 
its new surface, over which a membrane is formed. The flexion in the hypha tends 
to become rigid and permanent and the membrane at the point of bending stains 
more deeply with Congo red. 
Punctures and minute wounds. If a cell be punctured or minutely wounded 
. a thin stream of cell-content issues from the lesion and diffuses into the surrounding 
medium. The force of this jet gradually lessens and finally ceases, presumably with 
the equilibration of endosmotic and exosmotic forces, and the lesion becomes 
covered by a new membrane, so that frequently the region of injury can no longer be 
detected. Wounds of a diameter two-thirds that of the filament have been observed 
to heal in this way, and in some of the wider hyphae the exact manner of membrane 
restitution may be observed. Usually the new cell-wall substance is laid down 
simultaneously over the whole surface of exposed protoplasm, but occasionally 
regeneration proceeds by a centripetal diaphragm-like growth from the edges of the 
wound. 
Large wounds. Injuries greater in diameter than from one-half to two-thirds 
that of the cell rarely heal by restitution of the original membrane, and often the 
entire cell-content diffuses into the surrounding medium. If, however, the wound be 
situated towards one end of the cell a certain quantity of protoplasm may remain in 
the other end, and this either dies in situ or rounds off its naked surface and forms 
a transverse septum closing itself in. More rarely this moiety of cell-content has 
been observed to undergo a process of rejuvenescence and clothe itself in a completely 
new cell-membrane, forming what may be regarded as an aplanospore. The latter 
may germinate, producing a hypha which either pierces the original cell-wall, simu¬ 
lating a normal hyphal branch, or grows longitudinally through the parental filament, 
living apparently in a parasitic manner. 
Not infrequently a hypha is sheared across so that a cell is divided cleanly into 
two portions. The protoplasm usually diffuses from the open ends, but one or both 
moieties have been observed to round off their naked surfaces and form closing septa. 
Severe crushing or considerable laceration of a cell usually results in the death of 
the protoplast. 
Membrane formation by free protoplast. As a rule when a cell is injured part or 
all of the cell-content is ejected and is lost by diffusion into the surrounding medium. 
Rarely, however, the entire protoplast is released as a single unit, and of three such 
cases which were noted, one died, and two assumed a spherical shape and formed 
about themselves new cell-walls. Subsequently they elongated into slender hyphae 
giving rise to growths indistinguishable from rather delicate normal mycelium. 
In all instances of cell-restitution such as have been described growth proceeds only 
after the enclosure of the exposed protoplasmic surface by a cell-membrane. In the 
case about to be described, however, this procedure was reversed and a certain amount 
of free protoplasmic growth occurred prior to cell-wall formation. 
