. Bothalia. Botany. 180 MORPHOLOGY. Perithecia have been found on cankered areas of the twigs of the Avocado pear {Persea Americina). They are usually scattered, standing separate from one another. Sometimes, however, they occur in small groans of Wo to four, and occasionally they have been found so closely crowded as to form a pseudo-stroma, but no true stroma has been observed. They are buried in the cortical tissues, but at maturity the papillate ostiole breaks through to the surface and protrudes slightly. The form of a typical perithecium is shown in fig. 1, which is a camera-lucida drawi
. Bothalia. Botany. 180 MORPHOLOGY. Perithecia have been found on cankered areas of the twigs of the Avocado pear {Persea Americina). They are usually scattered, standing separate from one another. Sometimes, however, they occur in small groans of Wo to four, and occasionally they have been found so closely crowded as to form a pseudo-stroma, but no true stroma has been observed. They are buried in the cortical tissues, but at maturity the papillate ostiole breaks through to the surface and protrudes slightly. The form of a typical perithecium is shown in fig. 1, which is a camera-lucida drawing from a medial longitudinal section. The form is subglobose or broadly ellipsoid, 130-190 /j. in the horizontal diameter and 100-120 a in the vertical diameter. The average dimensions are about L70 « < 100 n?o Fig. 1. Section through a i>erithecium of Phymlmpora perseae. The wall is differentiated into two layers : the thickness of the outer layer is variable being thinner or almost absent at the base, and thickest at the sides near the base, where it is 16-24 fi thick. The pseudo-cells are brown, polygonal, 4-5 ji in diameter, or somewhat flattened. Within this there is an inner layer of delicate, colourless, compressed hyphae of much more uniform thickness. The papilla is usually central, bat may be oblique : it is 30-100 /jl long and 30-50 jjl in diameter, and its walls show two distinct layers similar to those observed in the sides of the perithecium ; the ostiole appears in section as a narrow passage between the walls of the papilla. The asci interspersed with paraphyses fill the cavity of the perithecium, and there are nameroos thread-like periphysee lining the neck and the inside of the 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 Botanical Research Institute (South Africa);
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1921
