226 DIVISION II.-—COURSE OF DEVELOPMENT OF FUNGI. 
.The. course of development in Eurotium and Penicillium 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 4) 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. Penicillium (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. Thggsporocarps of Penicillium 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. 

Fic. 107. J, J] Podosphaera pannosa. I chain of gonidia on the idi and ınycelium. // ripe 


the ascus a is emerging through the wall of the sporocarp % which has been rup byp III—V Podosph Cas: 
tagnei. III archicarp c with antheridial branch 5 on the mycelium. /Y older state; c archicarp invested by the 
hyphal branches of the wall, 4 antheridial branch. Vstill older state in optical longitudinal section; a ascus with its pedicel- 
cell, the product of ¢,# the wall 7, // 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 
