CARPOSPOREJE. 



311 



has been carefully investigated by De Bary with a view to the elucidation of these 

 points. The mycelium of this Fungus is found in the autumn growing upon the wet 

 dead leaves of the Vine. From it there arise erect segmented filaments, several milli- 

 meters in height, which ramify frequently towards their upper ends, numerous oval 

 conidia being developed on each branch, which are capable of immediate germination 

 and give rise to new mycelia. This stage of development of this Peziza was formerly 

 regarded as representing a distinct Fungus, known as Botrytis cinerea. Later on the 

 sclerotia are formed upon the mycelium, and although their origin from sexual organs 

 has not been actually observed, yet after the observations of Brefeld upon Penkillium 

 it cannot be doubted that such is the case. The . sclerotia appear as callosities of 

 various form, with a diameter of from ^ to i millimeter, in the tissue of the leaf which 

 is infested with the Fungus, and persist after that this tissue has undergone decay. 

 They consist of a dense felt of hyphae with a black cortex. If they be placed upon 

 moist earth soon after their formation, a great number of conidiophores are developed 

 from them. If, however, the sclerotia have remained inactive for some months, they 

 produce, when placed upon moist earth, small stalked cups, the flattened cavity of 

 which bears a hymenium in which ascospores are formed (Fig. 205) ; this fructification 

 is the Pe%i%a Fuckeliana. 



In addition to other genera which have small fructifications, this group includes also 

 the Helvellaceae, to which the genera Morchella (Morel), Hel'vella, Spathularia, and 

 Geoglossum belong. In these the fructification is borne on a stalk, and is either hat- 

 shaped or club-shaped, and attains a considerable size. The hymenium covers the 

 greater part of the surface of the fructification. 



(3) The ErysiphesB ^ form spherical perithecia upon the surface of the sub- 

 stratum which they inhabit, but they remain so small that they can scarcely be seen 

 with the naked eye, whereas the mycelium attains a considerable size. The investment 

 of the fructification is a delicate hollow sphere consisting of pseudo-parenchyma, sur- 

 rounding the few asci which spring from the carpogonium. 



The very numerous species of the genus Erysiphe (Mildew) occur upon the surface 

 of the leaves and green stems of Dicotyledons, and less frequently on those of Mono- 

 cotyledons also^. The ramified mycelial filaments extend over the epidermis, crossing 

 and re-crossing one another, and throw out haustoria at numerous points which pene- 

 trate into the cells of the epidermis. The mycelia are reproduced by means of conidia 

 which are abstricted in rows at the upper end of the erect unbranched conidiophores. 

 These reproductive organs, formerly termed Oidium, are the only ones at present known 

 in many species, as, for instance, in Erysiphe {Oidium) Tuckeri, the Fungus which pro- 

 duces disease in grapes. In many other species, however, the sexually developed fruits 

 may easily be found. Usually numerous filaments grow out from the cortical portion 

 of these fruits, which either attach themselves, like the mycelial filaments, to the 

 substratum, or remain quite free forming a delicate fringe. Both fruits and conidia 

 may be developed upon the same mycelium. 



The simplest mode of the formation of the fruit occurs in the sub-genus Sphxro- 

 theca, Fig. 207. The carpogonia and pollinodia are developed together at the points 

 at which the mycelial filaments cross one another, and are in contact from their first 

 appearance. They are both small lateral branches; the one from which the carpo- 

 gonium c is to be formed assumes an ovoid shape, and is then shut off by a septum ; 

 the one which is to become the pollinodium p curves over the apex of the carpogonium, 

 and a septum is formed in its curved portion. After fertilisation, filaments spring from 

 beneath the basal wall of the carpogonium, as also from the pollinodium (IV h), which 

 closely invest the carpogonium and grow up and come together over its apex ; they 



^ Tulasne, Selecta fungorum carpologia, I. Paris i860. — De Bary und Woronin, Beitiage ].mx 

 Morphol. und Physiol, der Pilze, 3rd series. Frankfort 1870. 



^ Perhaps Sphcerotheca pannosa (Rosarum) also penetrates into the tissues of its host. 



