. Bulletin of the British Museum (Natural History), Geology. . 204 A NEW TROCHILISCUS (CHAROPHYTA) agreement in the brown, translucent character, and in the presence of a very similar granulate decoration. There is also some evidence of an inner and an outer layer. The way in which the fossil membrane has been cracked and disrupted in T. podolicus is closely paralleled in Chara escheri. The thickening of the edges of the minute pores through a few membranes of T. podolicus suggests a wound reaction. The only respect in which the oospore membrane of T. podolicus differs from those of Recent and
. Bulletin of the British Museum (Natural History), Geology. . 204 A NEW TROCHILISCUS (CHAROPHYTA) agreement in the brown, translucent character, and in the presence of a very similar granulate decoration. There is also some evidence of an inner and an outer layer. The way in which the fossil membrane has been cracked and disrupted in T. podolicus is closely paralleled in Chara escheri. The thickening of the edges of the minute pores through a few membranes of T. podolicus suggests a wound reaction. The only respect in which the oospore membrane of T. podolicus differs from those of Recent and fossil charophytes is in the absence of spiral ridges. Even in some Recent species, however, the ridges may be reduced to little more than faint lines (Groves & Bullock-Webster, 1920: 58). Oospore contents. What is probably the true explanation of the origin of the vesicular contents of the oospore was suggested to me by Prof. T. M. Harris: that the vesicles represent starch-grains, the walls of the vesicles being the remains of the protoplasm and oil in which the starch- grains were embedded. The oospores of present-day charo- phytes contain oil and are tightly packed with rounded starch-grains. Some of these, showing the characteristic dark cross in polarized light, are represented in Text-fig. i. Mirande (1919) stained the protoplasmic film surrounding the starch-grains with haematoxylin and found that 'les manteaux mitochondriaux, en contact serre, forment un pseudo-tissu cellulaire avec meats, d'ou Ton pent, par une legere pression, faire sortir les grains d'amidon de leurs alveoles'. His fig. 4 shows 'un fragment de ce pseudo- parenchyme mitochondrial dans lequel quelques grains d'amidon, contractes par deshydratation par I'alcool, se sont decolles des parois'. The same kind of structure is well illustrated in a section of the endosperm of maize (Sachs, 1882; fig. 50A), which shows polyhedral starch- grains surrounded by 'thin plates of dried-up fine-grained protopla
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