. A text-book of mycology and plant pathology . Plant diseases; Fungi in agriculture; Plant diseases; Fungi. PATHOLOGIC PLANT ANATOMY 377 the axillary fibrovasqular cord is resolved into a circle of isolated bundles separated by chlorophyll-containing cells. 2. Callus ' Callus may be defined in the widest sense of the word as all cell and tissue forms produced subsequent to and as a result of injury. In many plants and plant organs, only a metaplastic change of the cells was incited by the injury (callus-metaplasia); in others, the cells laid bare showed an abnormal growth and were changed int
. A text-book of mycology and plant pathology . Plant diseases; Fungi in agriculture; Plant diseases; Fungi. PATHOLOGIC PLANT ANATOMY 377 the axillary fibrovasqular cord is resolved into a circle of isolated bundles separated by chlorophyll-containing cells. 2. Callus ' Callus may be defined in the widest sense of the word as all cell and tissue forms produced subsequent to and as a result of injury. In many plants and plant organs, only a metaplastic change of the cells was incited by the injury (callus-metaplasia); in others, the cells laid bare showed an abnormal growth and were changed into voluminous vesicles and sacs (callus-hypertrophy), or an increase of the normal tissue may result from wound stimuli (callus-homooplasia). The cells may be abundant after an injury owing to active cell division and heteroplastic tissue arises (callus-heteroplasia). When excres- cences arise, which are composed of cells very little differentiated and of the simplest form, they are called cataplasms. If produced after injury, they are found to differ greatly. The tissues produced after an injury, if resembling cork, are termed wound-cork, if similar to those of wood, they are called wound-wood and where we have the healing tissue composed of nearly homogeneous parenchyma, it is called simply callus. Callous tissue may be formed as wound tissue in very different plant groups. It has been found in the algal fungi and vascular cryptogams. The woody seed plants have been studied carefully as to the formation of callus, because of its economic importance in forestry and horticulture. Rose, poplar, or willow cuttings kept in moist air and at a proper temperature after a few days form a ring-like tissue excrescence from the cambiufn of the cut surface. This spreads out rapidly and finally closes over the wound. Such rolls of tissue have been called callus (callus, hard skin). Callus at least in its first stages appears in the form of a ring, some- times it is irregular in its formatio
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1917
