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DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



The course of development in Eurotium and Penieillium may be described in 

 the same words as in Erysiphe, making allowance for differences of form and for the 

 circumstance that the species in the two last genera are not epiphytic parasites, but 

 (for the most part) inhabit dead organic bodies ; here too we find frequent absence 

 of sporocarps where the vegetative conditions are not altogether favourable. The 

 gonidiophores of Eurotium (Figs. 94 and 35 b] are erect usually unicellular hyphal 

 branches inflated and bladder-like at the apex, where closely crowded radiating 

 sterigmata of uniform height are developed, and from these sterigmata spores are serially 

 and successively abjointed. The gonidiophores in Penieillium (Fig. 36) are narrowly 

 filiform, septate, and cymosely branched, and at their extremities, which are erect 

 parallel and close to one another and terminate at nearly the same height, spores are 

 formed by serial successive abjunction. The sporocarps of Penieillium glaucum have 

 at present been found only in dark or imperfectly lighted places where the supply 

 of oxygen is small, and chiefly on bread (Brefeld) ; I myself found them in abundance 

 on a heap of grape-skins, both growing naturally and after the spores had been sown 

 by hand. 



FIG. 107. /, // Podosphatra pannosa. 1 chain of gonidia on the gonidiophore and mycelium. // ripe sporocarp ; 

 the ascus a is emerging through the wall of the sporocarp h which has been ruptured by pressure. /// V Podotphaera Cat- 

 tagnti. Ill archicarp c with antheridial branch / on the mycelium. IV older state ; c archicarp invested by the 

 hyphal branches of the wall, p antheridial branch. / 'still older state in optical longitudinal section ; a ascus with its pedicel- 

 cell, the product off, h the wall. /, // after Tulasne. Magn. 600 times. 



The course of development of Melanospora parasitica again is on the whole very 

 like that of the above species, except that the gonidiophores short verticillately 

 branched hyphae with whorls of secondary branches, from which spores are acro- 

 genously and serially abjointed are very rarely produced, the work of propagation 

 falling chiefly to the ascospores. The peculiar parasitism of this Fungus will be 

 considered in Chapter VII. 



The ellipsoidal ascospores of Polystigma rubrum ripen in spring. They put out 

 a short tube on a moist substratum, and the extremity of the tube, which also swells 

 into an irregularly ellipsoidal form, receives the whole of the protoplasm, and is then 

 abjointed and forms a thick-walled spore-cell (gonidium, sporidium). This cell 

 readily germinates on a moist substratum, and on the epidermis of a foliage-leaf of 

 Prunus the germ-tube penetrates at once into the nearest cell and there puts out 

 branches, which then grow rapidly through the wall of the cell into the parenchyma 

 of the leaf. Here they grow at the cost of the tissue of the leaf and displace its 

 elements, but always covered by the epidermis, and in a few weeks' time they have 



