Some Tomato Diseases. F. T. Brooks and G. O. Searle. 191 
These forms are closely allied to one another and probably 
only represent strains of the same aggregate species. In the 
present state of our knowledge and methods of analysis, it is 
considered advisable to attempt to give names only to aggregate 
species of fungi and not to the smaller elementary species or 
strains of which the aggregate species consist. It has long been 
recognised by those who grow fungi in pure culture that many 
species show numerous forms which can only be differentiated 
one from the other by minor cultural characters, but under 
present conditions mycological systematy would become alto- 
gether too unwieldly if attempts were made to name these 
different cultural forms. 
It is proposed to place this group of forms as well as her- 
barium specimens Nos. I, 2, 5, 6, 7 and 8, in the genus Diplodina. 
It has already been pointed out that, as regards these fungi, 
the generic distinction between Phoma and Diplodina has 
broken down, but in view of the considerable percentage of 
septate spores in the pycnidia, Diplodina has been chosen as 
the generic name. The name Ascochyta is not used as the 
pycnidia do not occur in spots. Two species of Ascochyta have 
been recorded on decaying tomato leaves(13), A. Lycopersict 
Brun. with spores constricted at the middle, and A. socia without 
median constriction. These species have not been seen by us 
and have not yet been recorded in Britain. A. Lycopersici Brun. 
may be identical with the fungus now under consideration, but 
if so, it is preferable to place it in the genus Diplodina. Cooke's 
name Phoma Lycopersici(4) is deleted. Plowright’s Sphaeronema 
Lycopersici (12) found on tomato fruits may be identical with 
this, but it has not been possible to obtain the original specimen. 
It is doubtful whether Plowright* placed his fungus in the right 
genus as the neck of the pycnidium as figured in his paper is 
extremely short, and there is no mention of it in the diagnosis. 
The spores are about the same size as in our forms and the 
absence of septation is not remarkable. In view of these con- 
siderations and of the apparent loss of the type specimen, it 
seems advisable also to delete the name Sphaeronema Lycoper- 
sict. 
In considering the systematic position of this fungus, Mr J. 
Ramsbottom of the British Museum—to whom we are much 
indebted for help in the matter of nomenclature—called our 
attention to the description of Diplodina Lycopersici Hollés in 
Saccardo’s Sylloge Fungorum(r3). Although it has not been 
* Since this was written, Mr W. B. Grove informs us that Plowright’s idea 
of Sphaeronema depended upon the presence of a ‘‘ globule”’ of extruded spores 
at the mouth of the pycnidium, and not upon the presence of a “beak” as 
understood by Saccardo. 
