Fungi, Ascomycetes, Ustilaginales, Uredinales . Fig Uromyces Poae Raben.; young aecidium,? 370; after Blackmail and Fraser. Puccinia Poarum (Blackmail and Fraser 06), Puccinia Falcariae (Ditt-schlag 10)), or directly below the epidermis (Phragmiditim violacaim (Black-man 04), Uromyces Poae (Blackman and Fraser 06) (fig. 171), PucciniaClaytoniata (Fromrne 14)); these hyphae give rise to a more or less regularseries of uninucleate cells. These are the fertile cells, but, before developingfurther, each, at any rate in the relatively primitive forms (caeomata), maycut off one or occasionally more
Fungi, Ascomycetes, Ustilaginales, Uredinales . Fig Uromyces Poae Raben.; young aecidium,? 370; after Blackmail and Fraser. Puccinia Poarum (Blackmail and Fraser 06), Puccinia Falcariae (Ditt-schlag 10)), or directly below the epidermis (Phragmiditim violacaim (Black-man 04), Uromyces Poae (Blackman and Fraser 06) (fig. 171), PucciniaClaytoniata (Fromrne 14)); these hyphae give rise to a more or less regularseries of uninucleate cells. These are the fertile cells, but, before developingfurther, each, at any rate in the relatively primitive forms (caeomata), maycut off one or occasionally more terminal sterile cells which ultimatelydegenerate. The fertile cells may unite laterally in pairs (fig. 172), so thatbinucleate compound cells are formed ; they may similarly pair with the VIII] UREDINALES 201. Fig. 17:. Phragmidium speciosum Fr.; a. fertile and sterilecells; b. fusion of two fertile cells; after Christman. 1 ells below them (Fromme 14), or each may receive a second nucleus bymigration from a neighbouring vegetative cell (fig. 1751. In each case theynow constitute the basal cells of the rows of sporesand theyproceed at once tocutoffaecidiospore mother-cells, each of which in turndivides to separate a smallintercalary cell below fromthe aecidiospore above. Exceptionally binucle-ate cells may be observedbefore the fertile layer isdifferentiated. In PucciniaPoarittn nuclear migrationssometimes take place be-tween the vegetative cellsat the base of the veryyoung aecidium. Thesecells may grow up, eitherat once or after division, toform fertile cells. The aecidiospores, then,are the products of asexualprocess by means of whichtwo nuclei become associated within thelimits of a single protoplasmic mass, form-ing the dikaryon or synkaryon of nuclei thus brought together do
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
