238 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI, 
which have been made in previous sections. I shall retum in a later page to the matters 
which, as I have said, do not belong to this place. 
DETERMINATION OF IMPERFECTLY KNOWN ASCOMYCETES. 
Section LXVII. The facts detailed in the foregoing pages were established at 
first from a comparatively small number of species, but they nevertheless enable us to 
pass judgment with tolerable certainty on all the varied phenomena which have been 
observed in the countless forms of the Ascomycetes, especially the Pyrenomycetes 
and the Discomycetes ; they are a frame in which the latter may be set. It must at 
the same time be remembered that very many of these phenomena were known, 
named, and provisionally disposed of according to the best knowledge of the time 
before a secure basis was laid for a decision respecting them, and that it 
was by starting from single phenomena that this basis was gradually reached. 
Especially should it be remembered (see section XXXII) that at first every distinct 
orm was supposed to represent a distinct species; the gonidiophores of Sclerotinia 
Fuckeliana were made a species under the name of Botrytis cinerea, the sclerotia 
another species ag Sclerotium echinatum, while the sporocarps by themselves were 
made a species of Peziza; in Erysiphe the gonidiophores were supposed to be a 
species of the genus Oidium, and only the perithecia were assigned to Erysiphe. 
The researches of Tulasne first led gradually to an understanding of the real 
condition of things to which he gave the name of pleomorphism, and to him we are 
chiefly indebted for the distinguishing and naming of the possible forms in the 
development of a species. These researches rested on the broad foundation of the 
comparative observation of numerous forms, of their cohabitation, of their anatomical 
connection, and their succession in time. Pursued in this way they arrived on the 
whole at the truth, and it is a small diminution of their merits that they should have 
given rise to some erroneous views on special points, or that they occasionally made 
a too extensive application of schemes drawn from a number of observations. This 
latter proceeding led indeed to more important mistakes in the hands of some 
less careful followers. The task of critical examination could only be satis- 
factorily performed after more profound investigation, aided especially by complete 
experiments in artificial cultivation; and this has resulted in showing that, owing to the 
great number of the species, the differences in the course of development between 
the homologous and analogous terminal points which are often very important, and 
the frequent symbiotic relation social or otherwise between several species, the 
complications may be much greater than would appear at first sight and than can be 
expressed by one scheme. Various controversies also have arisen, as appears from 
the case of Pleospora described above, out of all these labours and efforts which are 
still far from their final conclusion. Much that belongs to this subject is only of 
interest in connection with the individual cases and must be referred to in the descriptive 
literature. We can here call attention only to the chief points of view, but it will be 
well first of all to enumerate briefly the chief phenomena and members of the 
development observed in the species above described. 
1. From the ascospore is developed a thallus which only produces asco- 
genous sporocarps, or archicarps. which produce. these sporocarps together with 
