. An introduction to vegetable physiology. Plant physiology. 428 VEGETABLE PHYSTOLOGY on the chief vegetative functions, while the gametophyte is the small pro thallium (fig. 174). Even without going-beyond the Ferns we can notice as we pass through the several divisions of the vegetable kingdom that the predominant form of the plant has changed. In the Thallophyta it is always the gameto- phyte ; the sporophyte is not universal there and is never more than a small structure, which nearly always remains attached to the gametophyte. In the Bryophyta the two phases are more nearly alike in degre
. An introduction to vegetable physiology. Plant physiology. 428 VEGETABLE PHYSTOLOGY on the chief vegetative functions, while the gametophyte is the small pro thallium (fig. 174). Even without going-beyond the Ferns we can notice as we pass through the several divisions of the vegetable kingdom that the predominant form of the plant has changed. In the Thallophyta it is always the gameto- phyte ; the sporophyte is not universal there and is never more than a small structure, which nearly always remains attached to the gametophyte. In the Bryophyta the two phases are more nearly alike in degree of development; the gametophyte is always the vegetative body, while the. Pig. 174.—Pkothallium (Gametophyte) of Pern. spoi*ophyte often shows the greater histological differentia- tion. It is always parasitic upon the gametophyte and never attains a higher degree of morphological value than a thallus. In the Pteridophyta the predominance of the sporophyte is very marked, and as higher and higher groups of plants are reached it becomes still more pronounced, the gametophyte ultimately being reduced to microscopic dimensions. We • encounter for the first time in the group of the Pteridophyta, the Ferns and their allies, a phenomenon which becomes of constant occurrence in all groups above. 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 Green, J. Reynolds (Joseph Reynolds), 1848-1914. Philadelphia, P. Blakiston
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