TAXONOMIC CHARACTERS OF ALTERNARIA AND MACROSPORIUM 443 
The most instructive results appear in the sixth column of the 
table where the maximum and minimum lengths and breadths of the 
spores are given under conditions such as would obtain in describing 
a new species. Here there was a variation of over 41 percent of the 
highest maximum measurement returned for the length of the spores. 
The variation for the minimum lengths was greater. Assuming vari- 
ation equal to that shown in column 6 of Table A, 34 species of Macro- 
sporium and 5 species of Alternaria in the "Sylloge Fungorum" are 
inseparable by measurements of both length and breadth. 
Applying to all the species of Alternaria and Macrosporium in the 
"Sylloge Fungorum" the variability shown in column 6 of Table A, 
they can be combined into thirteen groups, taking into consideration 
the measurements for both length and breadth of spores. In other 
words, if other characters are disregarded, in so far as actual spore 
measurements are dependable, there are only thirteen species of Ma- 
crosporium and Alternaria adequately described in the "Sylloge 
Fungorum." 
Study of Exsiccati 
Following the study of descriptions in the ''Sylloge Fungorum," 
examination was made of the specimens of Macrosporium and Alter- 
naria in the exsiccati immediately available. One hundred and thirty- 
four specimens labeled as 85 species, were found. Of this number 17 
were marked '*sp. n." i. e., of or nearly of the value of type material. 
Eighteen other species not marked "sp. n." were found in the exsiccati 
of the authors or one of the joint authors of the species. This gave a 
total of 35 species, the material of which can be regarded as reasonably 
authentic. 
Mounts were made from each of the specimens, from which spore 
and conidiophore measurements, and the character of each, were 
recorded. The nature of the growth, whether apparently parasitic or 
saprophytic, was also recorded and the descriptions so made were 
compared. There was no doubt that in the collection, many speci- 
mens morphologically indistinguishable appeared under different 
names, and that in some instances the same name was given to speci- 
mens which were in no way similar or which could readily be dis- 
tinguished from each other. 
In the following summary of the study of the exsiccati the names 
are given as they appeared on the specimen, followed by the title of 
