232 DIVISION II- -COURSE OF DEVELOPMENT OF FUNGI. 



in special receptacles, as adaptations to special circumstances of development, the 

 further consequence of which is the establishment of diclinism. 



It must be admitted that comparisons of this kind are always somewhat insecure 

 and readily afford too much room for the play of fancy, if they are not supported by 

 a more complete series of well-known intermediate forms than can at present be 

 produced in this case. The comparison in the text may be offered with this 

 reservation attached to it. It appears to me to fit in quite naturally with ascertained 

 facts ; nor is it too much to expect that the intermediate forms that are wanted will 

 be found, if we consider how few of the whole number of Ascomycetes have been 

 examined up to the present time. 



If we compare the whole course of development of the Ascomycetes in which 

 this course is fully known with that of the groups of Fungi described in previous 

 sections, we become distinctly aware of a parallelism between Eremascus and the 

 Ascomycetes, which are provided with archicarps and antheridial branch on the 

 one side, and the Mucorini, Peronosporeae, and Saprolegnieae on the other. A 

 thallus proceeds from the carpospores (ascospores, oospores), and terminates its 

 development with the formation of an archicarp and antheridial branch and of 

 the new carpospore which is formed from them. To this the whole course of the 

 development is limited in many cases, as in Eremascus, Pyronema, and species 

 of Ascobolus on the one side, and on the other in Pythium vexans and Artotrogus ; 

 in most cases it is interrupted by the formation of other spores, the gonidia. The 

 gonidia of a species are sometimes all of one kind, as in Erysiphe and Peronospora, 

 sometimes of more than one kind in the same species. The parallelism extends 

 even to close resemblance in form in organs of the same name in certain groups. 

 Eremascus might, to judge from Eidam's description, be almost ranked with the 

 Mucorini, especially the Piptocephalideae ; on the other hand, none of the essential 

 developmental characters of an Ascomycete are wanting in it. In the form of its 

 archicarps it is perfectly like Penicillium, Gymnoascus, Eurotium and other genera. 

 There is also a great amount of agreement in respect of the thallus, formation of 

 the gonidia, archicarp, and antheridial branch between the Ervsipheae, especially 

 Podosphaera, on the one hand, and some Peronosporeae on the other 1 . These 

 groups therefore establish a nearer connection between the Ascomycetes in question 

 and the Peronosporeae ; a convergence of the two groups which amounts to 

 actual contact and may be regarded as phylogenetic affinity. This connection with 

 the Peronosporeae is closest in Podosphaera, because there caeteris paribus not 

 only the archicarp and antheridial branch arc like the same parts in the Pero- 

 nosporeae, as, for example, in Phytophthora omnivora, but the ultimate develop- 

 ment also of the archicarp only goes a little further ; the eight-spored ascus with 

 its stalk proceeds from division of the cell twice repeated, while in Phytophthora the 

 archicarp becomes the oogonium with the oospore. Erysiphe is closely con- 

 nected with Podosphaera, in which the archicarp by repeated cell-division and 

 branching gives rise to a number of asci, and all the rest of the Ascomycetes in 

 question with Erysiphe, as appears plainly from the details which have been given 



For a more extended comparison see Beitr. IV, p. 109. 



