. A manual of botany. Botany. 29 CHAPTER III. Group I. THALLOPHYTA. Fig. 779. This group includes the AlgEB, the Fungi, and the Lichens. It embraces plants of widely different habit and complexity of structure, both morphological and anatomical. In the lowest forms they are characterised by extreme simplicity in both these respects, the plant body being sometimes a single cell, sometimes a thaUus consisting of filaments or plates of cells. In the higher forms, on the contrary, the plants are often bulky and formed of masses of tissue showing some considerable histo- logical differentiation; th
. A manual of botany. Botany. 29 CHAPTER III. Group I. THALLOPHYTA. Fig. 779. This group includes the AlgEB, the Fungi, and the Lichens. It embraces plants of widely different habit and complexity of structure, both morphological and anatomical. In the lowest forms they are characterised by extreme simplicity in both these respects, the plant body being sometimes a single cell, sometimes a thaUus consisting of filaments or plates of cells. In the higher forms, on the contrary, the plants are often bulky and formed of masses of tissue showing some considerable histo- logical differentiation; their form may display both root and shoot, the latter exhibit- ing stem and leaves. Again these bulky masses may be distinctly thalloid. The simplest Thallo- phyte shows no histologi- cal differentiation, being only a single cell such as Yeast, or Hsematococcus. A chain of cells liie Nostoc (fie/. 779) is almost as simple, though cells of different appearance may be present in the chain. Usually a filament of this kind has its cells independent, and sepa- rated from each other by ceU-walls. In a good many cases these separating walls are not formed, and the organism consists of a tubular body with an external wall, on the inner face of which lie the constituent cells, whose protoplasm is con- tinuous throughout. The composite nature of this structure is recognised by the presence of numerous nuclei. A structure like this is called a Cosnocyte. The filament in other cases is much like this, but some of. Fig. 779. Filaments from a Nostoc colony. After 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. London, J. & A. Churchill
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