184 Transactions British Mycological Society. 
This Group A includes the following forms: 
Form A: which is an authentic specimen of Phoma destructiva 
(Plowr.) C. O. Jamieson, from America. 
Form B. 
Form C: which possesses an Alternaria form of spore as well 
as a pycnidial stage. 
Forms EF, i, J. 
Form L: which is pycnidial but shows differences from the 
other forms in its wider infective powers and greater percentage 
of septate spores. 
Forms M, P, Q. 
Form T: which is a specimen of Ascochyta Pist Lib. 
Form U: no fructifications were formed by this. 
Group B consists of those forms which can be placed either 
in the genus Colletotrichum or Gloeosporium, and includes: 
Form D: which is an authentic culture of Colletotrichum 
phomoides (Sacc.) Chester from America. 
Forms K, K 2 and S. 
Group C consists only of Form N which is a typical species 
of the genus Fusarium. 
In studying the various forms of Group A it was found that 
these showed great variability in characters which are generally 
looked upon as specific, such as size of spores, septation of 
spores, guttulation and shape of spores, and one was forced to 
the conclusion that a number of so-called species in genera 
like Phoma, Ascochyta and Diplodina, are nothing more than 
varieties of one and the same fungus. In fact, it is difficult to 
see how a final decision is to be made in many cases unless the 
investigator has the opportunity of carrying out a large number 
of cultural trials on artificial media and also cross inoculations 
on to various hosts. A comparison of the microscopic char- 
acters found in the pycnidial forms included under Group A 
will now be made: 
MICROSCOPIC CHARACTERISTICS OF THE VARIOUS FORMS 
INCLUDED IN GROUP 4 (PYCNIDIAL FORMS) ON TOMATO 
FRUITS AND CULTURE MEDIA. : 
Form A. 
PYCNIDIA. 
Description given by 
Miss Jamieson (q.v.) 
Scattered to aggregate, most 
abundant towards centre of 
spot, subcutaneous later erum- 
pent, glabrous, brownish black, 
subglobose, slightly papillate, 
Description of authors’ 
cultures 
Pycnidia varying greatly in 
size, sometimes single, some- 
times compound with two or 
more ostioles (sometimes as 
many as four). Pycnidia 
