. The anatomy of woody plants. Botany -- Anatomy. 172 THE ANATOMY OF WOODY PLANTS this involves no erroneous hypothesis of their relation to the pith. It is therefore necessary to distinguish carefully between wood rays and gaps or discontinuities in the woody cylinder originating as a result of conditions described above. It seems quite evident that the failure to realize this distinction invalidates investigations on the woody cylinder involving the confusion of thought elucidated by the items in t e accompanying figure. The last para- graph will have con- vinced the reader that radial bands
. The anatomy of woody plants. Botany -- Anatomy. 172 THE ANATOMY OF WOODY PLANTS this involves no erroneous hypothesis of their relation to the pith. It is therefore necessary to distinguish carefully between wood rays and gaps or discontinuities in the woody cylinder originating as a result of conditions described above. It seems quite evident that the failure to realize this distinction invalidates investigations on the woody cylinder involving the confusion of thought elucidated by the items in t e accompanying figure. The last para- graph will have con- vinced the reader that radial bands of parenchyma, formed as a result of cam- bial activity, can- not accurately be described as medul- lary rays. We are now in a position to consider the situa- tion presented by the stem of peren- nial seed plants of gymnospermous af- finities. Fig. 123 reproduces part of a transverse section of a stem of the white spruce, Picea canadensis. The woody cylinder is characterized by numerous radial bands of parenchyma, appar- ently in every instance taking their origin from the medulla or pith. Further, there are present broad outwardly directed bays from the medullary region which represent the gaps correspond- ing to outgoing leaves (for in the gymnosperms, in contrast to the lycopods and their allies, the leaves are related to foliar gaps). A superficial examination of the figure would justify the applica- tion of the term medullary ray both to the narrow radial bands of parenchyma and to the broader bays extending from the pith. The considerations advanced in the last paragraph make it clear,. FIG. 123.—Stem of Picea, showing apparent relation of wood rays to Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jeffrey, Edward C. (Edward Charles), b. 1866. Chicago, Ill. , The University of Chicago Press
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