. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. 212 PROTOBASIDIOMYCETES [CH. â â¢:⢠:â m Fig. i88. Uromyces Poae Raben.; conjut^nte divi<;ions in aecidium, x 1330; after Blacliman and Fraser. fication and in some cases it shows but few of the characters of normal mitosis. In the spermatial hyphae of Gymnosporangium clavariaeforme, for example, Blackman has described a condensation of the nucleus to form a deeply staining body out of which the nucleolus is squeezed. The chromatin is drawn apart into two apparently homogeneous masses between which a kinoplasmic thread represents the
. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. 212 PROTOBASIDIOMYCETES [CH. â â¢:⢠:â m Fig. i88. Uromyces Poae Raben.; conjut^nte divi<;ions in aecidium, x 1330; after Blacliman and Fraser. fication and in some cases it shows but few of the characters of normal mitosis. In the spermatial hyphae of Gymnosporangium clavariaeforme, for example, Blackman has described a condensation of the nucleus to form a deeply staining body out of which the nucleolus is squeezed. The chromatin is drawn apart into two apparently homogeneous masses between which a kinoplasmic thread represents the spindle. A similar process takes place in the division of the conjugate nuclei in this and other forms, but the spindle is generally recognizable somewhat earlier, at a time when the chromatin of each nucleus still forms a single mass. As a rule the spindles of the conjugate nuclei lie parallel one to another (fig. 188). Moreau, following Sappin-Trouffy, has recorded two chromosomes or chromatin masses formed from each nucleus in various Uredi- neae. Olive on the other hand in Triphragmidium Ulmariae and Uromyces Scirpi has found a clearly defined spindle and centrosomes and has succeeded in recognizing several separate chromosomes; a similar state of affairs has been recorded by Christman for Phragmidium speciosum so that it would ap- pear that the different species of rusts are at dissimilar levels in this matter, though a further study of carefully fixed material might be undertaken with ad- vantage. In all cases, however, the divisions of the fusion nucleus of the teleutospore are much more elaborate than those in the vegetative cells and show some of the characteristics of a meiotic In Coleosporium (fig. 189) the fusion nucleus at first possesses a well-marked reticulum of interlacing threads. This undergoes a stage of concentration in one part of the nuclear area, which no doubt corresponds to synapsis, and afterwards loosens out, increases in thickness and forms a
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
