CONTRIBUTIONS TO THE HISTORY OF THE DEVELOPMENT OF 
THE PYRENOMYCETES. * 
(Plate IX.) 
By Franz von Tavel. 
The Ascomycetes have already been the object of many researches 
resulting in a series of most interesting facts which in turn always sug¬ 
gest new questions. To solve these requires investigations in two di¬ 
rections. First, the development and significance of the separate or¬ 
gans, especially of the pycnidia and perithecia, should be better estab¬ 
lished. Athough much has been done in this respect, still the manifold 
forms of the Ascomycetes leave many new facts to be expected, and 
the results already obtained are too scattered to admit of any general¬ 
ization. Second, the life history of the pleomorphic forms demands 
thorough investigation. We know a large number of pycnidia and 
other gonidia forms, and conclude that each represents a stage in the 
development of an Ascomycete, but this has been definitely proved in 
only a very few cases. 
What follows contains a series of observations in the two directions 
already indicated, having as their object some gonidia forms and Pyre - 
nomycetes of doubtful relationship, but not giving a complete chain of 
development. We will first attempt to solve the question as to what 
cycle of development the common Gloeosporium nervisequum , (Fckl.) 
Sacc., a dangerous enemy to the sycamore trees, belongs. For reasons 
given below the question must remain almost entirely unanswered, but 
other forms of fungi were found in the course of these investigations. 
A pycnidium, Discula platani, (Pk.) Sacc., is suspected of belonging to 
the same cycle of development as the Gloeosporium and was consequently 
very closely investigated. Together with this Discula appeared a Fe- 
nestella whose life history could only be established to a certain degree 
of completion. A Cucurbitaria found growing with the two other 
forms was studied in relation to the development of its pycnidium, more 
exhaustive observations being prevented by the lack of material. In 
what follows I have brought together my observations on these four 
forms. 
It should be mentioned that the three last-named fungi live on dry 
branches. It is well known that these, like lichens that grow upon 
bark, can not be cultivated except with difficulty. Hitherto they have 
only attained a limited age in culture fluids. It is extremely difficult 
to cultivate them on dry twigs because it is impossible to sterilize other 
twigs without destroying the objects of our observations, and foreign 
fungi, which make observations difficult and results uncertain, invade 
the cultures and in many cases so get the upper hand as to destroy all 
other fungi. Tricothecium roseum , Lk., is an especially dangerous fungus. 
* Bot. Zeitung, 1886, p. 824. 
