The structure & development of the mosses and ferns (Archegoniatae) . pical cell. from the large prothallial cell (Fig, 169, B). The young root-hair contains chlorophyll, but not so much as the larger germination proceeds the chloroplasts separate and increasein size. They are often arranged in lines extending from thelarge nucleus to the periphery of the cell. As a general thing, 340 MOSSES AND FERNS CHAP. the growth of the prothallium is exactly opposite to that ofthe first rhizoid (bi-polar germination), and Kny ^ lays a gooddeal of stress upon this, as distinguishing Osinunda from
The structure & development of the mosses and ferns (Archegoniatae) . pical cell. from the large prothallial cell (Fig, 169, B). The young root-hair contains chlorophyll, but not so much as the larger germination proceeds the chloroplasts separate and increasein size. They are often arranged in lines extending from thelarge nucleus to the periphery of the cell. As a general thing, 340 MOSSES AND FERNS CHAP. the growth of the prothallium is exactly opposite to that ofthe first rhizoid (bi-polar germination), and Kny ^ lays a gooddeal of stress upon this, as distinguishing Osinunda from thePolypodiaceae ; but it is not at all uncommon for O. Claytoniana,especially, to have the axis of growth of the rhizoid almost orquite at right angles to that of the prothallium, exactly as inthe Polypodiaceae. Where the germination is truly bi-polarthe exospore is pushed up with the growing prothallium, andappears like a cap at its apex, but if the root-hair is lateral,the exospore remains at the base. In O. Claytoniana there are usually several transverse walls. B.
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Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
