68 DIVISION I.—-GENERAL MORPHOLOGY, 
The spore-formation in Ustilago and Geminella, which will be further considered 
in section LV, appears from Winter’s observations on Geminella and Ustilago 
Ischaemi! to be nearly allied to the cases just described. More certainly is this the 
case with many acrogenously formed so-called sep/are spores, as those of Puccinia 
(Fig. 26 4) and Phragmidium, and many forms of Hyphomycetes, the systematic 
position of which has not yet been exactly determined, Trichothecium, Arthrobotrys 
Fusiporium, &c.; also forms which we now knowas gonidiophores of the Pyrenomycetes, 
such as Fries’ groups of the Dematieae and Sporidesmieae, Helminthosporium, 
for example, Cladosporium, Alternaria, Sporidesmium, Phragmotrichum, Polydesmus, 
Melanconium, Stilbospora, Coryneum, Exosporium, and very many other forms. See 
Figs. 21 and 34, and section XXIX. 
Section XVII. The inception (Anlegung) of acrogenously produced spores 
takes place in every instance according to one or other of the processes which have now 
been described. In some also ripeness, that is the capacity for further normal develop- 
ment, and the size, form, and structure which indicate this capacity, is reached, as has 
been repeatedly stated above, when the delimitation is completed. This is the case, 
for example, in Cortictum amorphum (Fig. 30) and in many, perhaps in all the 
Basidiomycetes, and to a certain degree in Cystopus Portulacae (Fig. 33); in the 
case of many other small spores attached by a very narrow stalk it is not possible to 
speak with certainty on this point, because the minuteness of the point of insertion 
renders it impossible to determine the exact moment when delimitation by the cross 
septum is effected. On the other hand, many cases are known in which after acro- 
genous delimitation the cross septum undergoes a considerable amount of growth before 
it is mature, and it obtains the necessary food for this purpose from the sporophore ; 
this is the case, for example, in all the species of the Uredineae mentioned in the pre- 
ceding sections, and in Eurotium and Penicillium, &c. In a rapidly growing successive 
chain in these species the majority of the younger members are still immature, and 
the nutrient material, so far as it comes from the sporophore, must pass by the younger 
cells to reach the older more distal ones. 
Many acrogenous spores are Zersisien! on the sporophore after they are mature, 
and are carried away from the place where they were formed only by accidental 
external mechanical agencies, as the teleutospores of Uromyces, Puccinia, and 
Phragmidium, the large gonidia of Hypomyces and many other septate forms above 
mentioned. 
But the larger part of these spores are defached from the sporophore as soon as 
they are mature by the aid of internal causes, which during the process of ripening 
bring about certain changes in the original condition and thus render the ultimate 
separation possible. The three chief modes known to us in which this purpose 
is effected are the disappearance of the sporiferous structure (Schwinden der Trager), 
abscısion? (Abschniirung), and adyection ® (Abschleuderung). 
The disappearance of the sporiferous structure is most common among the 
Gastromycetes, in which, when the spores are ripe, not only the basidia, but usually 

1 Flora, 1876, Nr. 10, 11. ? See note on page 61. 
3 See note on page 84. 
