Archive image from page 321 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana05todd Year: 1859 TJie same after impregnation, 150 diain. The papilla has been broken off in making the preparation. direction of growth of this structure, which is the first leaf of the embryo, is obliquely up- wards. In its axil is formed the primary axis; Fig. 183. of the vertical series of sporangia which cor- responds to each valve, one only of the ori- ginal central cells continues its development, the rest becoming abortive, and finally disap- pearing. The four spor
Archive image from page 321 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana05todd Year: 1859 TJie same after impregnation, 150 diain. The papilla has been broken off in making the preparation. direction of growth of this structure, which is the first leaf of the embryo, is obliquely up- wards. In its axil is formed the primary axis; Fig. 183. of the vertical series of sporangia which cor- responds to each valve, one only of the ori- ginal central cells continues its development, the rest becoming abortive, and finally disap- pearing. The four spores, which are formed just as in Selaginella, at length become free by the absorption of the cell in which they are enclosed, and for a time continue to en- large equally, while their walls are thickened by internal gelatinous deposition. Soon, how- ever, one begins to exceed the rest in growth, and finally occupies the whole cavity of the sporangium, which is subsequently burst by the swelling of the exospore, which is pro- duced when it is subjected to the influence of moisture. 101. The microspores are developed precisely as in Selaginella. The exosporal membrane Fig. 184. Embryo of Pihdaria f/hlmlifera, 10 diam. The embryo is still enclosed in the prothallium, the tissue of which has expanded so as to form an investment for it. a, remains of papilla of archegonium with its canal; 6, first root; c, first leaf; d, primary axis; e, cavity of macrospore. and soon after, as a lateral development from this last, the second leaf. In the meantime the first root makes its appearance as a rounded projection, which grows from the upper sur- face of the embryo, in a direction opposite to that of the first leaf. Both of the last-men- tioned organs finally burst through the remains of the prothallium, and become free. 100. Sporangia and spores.—The organ in which the sporangia of Pilularia are contained is an egg-shaped body, supported on a short, curved pedicle, which springs directl
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