160 Weston .— The Development of 
these abnormal cases, however, escape of the sporangiospores also takes 
place by rupture of the wall near the papilla or elsewhere (Fig. 39). 
When the individuality of the spores is finally established, they are 
distinctly polygonal; and the sporangium wall presents a plane, even 
contour (Fig. jo). Gradually, however, the spores imbibe water, swell, 
and become spherical; and as their flattened surfaces of mutual contact 
round out, the spores are separated, and the sporangium wall becomes 
tightly stretched over their bulging outer surfaces. As this process of 
swelling and rounding goes on, the restraining wall becomes increasingly 
Text-Fig. t. Escape of the sporangiospores. From camera lucida drawings of living material. 
1, 2. A sporangium which burst at the side, allowing a large number of spores to escape. Note 
adherence of the spores. 3, 4. A small sporangium just before and just after bursting at the tip. 
5. 6. A short, broad sporangium from which a number of spores were forced out, rupturing the wall 
near the base. 
distended and eventually bursts (Fig. 13). Liberation of the spores does 
not take place at once. When the membrane is ruptured, the spores in 
the immediate region of the break are forced out, relieving the pressure. 
The elastic membrane, however, still restrains the remaining spores, and 
after a few minutes the distension among these may become sufficient to 
push out those most favourably situated. 
The point at which the bursting of the sporangium membrane takes 
place varies according to conditions (Text-fig. 1). When the sporangia are 
long and slender, the longitudinal expansion, augmented by the upward 
bulging of the sporangial septum, far exceeds the lateral expansion, and the 
sporangium membrane is generally ruptured at the tip. In broadly clavate 
