254 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI. 
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certain conditions do really fill up the gaps in our knowledge, that is, are able to 
produce the typical ascocarp of an Ascomycete; or whether there are species 
which in their known characters do come near to typical Ascomycetous genera and 
may even be included in them, but do not at present actually produce the ascocarp 
of an Ascomycete. In the latter case a further question arises, whether and how 
far the problematic defect comes from the loss of the capacity or from its having 
never been possessed. The attempt to examine and answer these questions leäds us 
necessarily into the domain of conjecture, and forces upon us the reservations here 
proposed. Every new unexpected fact may change the grounds of the decision. 
If we begin with the second question from the stand-point of our present knowledge, 
we must conclude that the plant has Jost the capacity, as long as the views on the 
unity and affinity of all the Ascomycetes and on their homologies and connection 
with the Peronosporeae, which were developed above in section LXVI, are not shown 
to be incorrect. This is the necessary result of what has been already stated and does 
not require to be again explained. Whether the loss has in every case directly‘ 
befallen the species 5 under observation, or another z from which 4 is descended, 
must remain an open question and is not an essential element in the matter. The 
assumption of such a loss would also be in harmony with other known facts in the 
Fungi which imply retrogression in the development of a species with excision of 
certain members (see below in section LXXXII). Moreover there are distinctly observed 
facts within the group in question, which enable us to form a clear idea of the way 
in which this loss may be occasioned ; but these very facts themselves compel us to 
be cautious and to leave it to time to give a decided answer to the second as well as 
to the first of our questions. These facts are, first, that some species of Ascomycetes, 
as has been already pointed out more than once, form their ascocarps only under 
fixed and narrowly limited conditions, while they reproduce themselves by forming 
gonidia under very varied conditions. Of this fact Penicillium, Peziza Fuckeliana, 
Zopf’s Fumago, and the species of Hypomyces described above, are examples. 
Secondly, there are pleomorphic species which also show a marked tendency to the 
reproduction of like forms when the conditions remain unchanged, that is, each 
spore-form chiefly produces its own form again, more rarely a form of another kind. 
Peziza Fuckeliana is an excellent example of this. If the gonidia of this Fungus, the 
spores of ‘Botrytis cinerea,’ are sown in a good nutrient solution, grape-juice for 
instance, the product is always a filamentous mycelium with copious formation of 
gonidia. If the ascospores are sown in the same solution under exactly the same 
conditions, a mycelium is developed with sclerotia, but gonidiophores never or 
scarcely ever appear ; wherever they have appeared they have appeared singly, and 
cases of the kind are highly exceptional and not free from suspicion on the score of 
the purity of the sowing. If similar sowings are made on suitable dead leaves of 
Vitis or Castanea which have been boiled to free them as far as possible from 
foreign spores, sclerotia are generally developed ; if ascospores are sown, sclerotia 
only are formed without filamentous gonidiophores ; if gonidia are sown, the sclerotia 
are accompanied by an abundance of gonidia which spring from the filamentous 
mycelium. In cultures of the latter category single gonidiophores may certainly be 
produced from a sowing of ascospores, just as they may be developed, as is well 
known, from the sclerotia (see on page 224). The general result which is the 
