TAXONOMIC CHARACTERS OF ALTERNARIA AND MACROSPORIUM 44 1 
on artificial media, found that they formed chains of conidia and 
placed them in the genus Alternaria. Bioletti (3) reported securing 
pure cultures of Macrosporium sp. and Alternaria sp. from olives in 
California. Others have reported isolating species of one or the other 
genera from various sources and growing them in pure culture under 
conditions where the morphology of the fungi ought to have been 
pretty certainly ascertained, but by far the greatest amount of liter- 
ature on the two genera deals with their pathogenic effects or with the 
mere description of species. 
Miyake (14), Prillieux and Delacroix, (17), and others (4) have 
shown by careful experiments or have suggested that many of the 
specific names are synonyms. Constantin (4) and Planchon (16) 
have reported great variations in Alternaria due to growth on different 
media. Planchon (16) expresses the opinion that Macrosporium is 
merely Alternaria with dissociated conidia. No extensive comparative 
work, either between the two genera or between species of the two 
genera, has yet been undertaken. 
III. METHODS IN GENERAL 
To aid in the comparison of published descriptions, a tabulation 
of the species and varieties of Alternaria and Macrosporium given in 
the "Sylloge Fungorum" was made on the basis of spore length, the 
species being arranged according to the maximum length given. 
Specimens from all available exsiccati were studied and compared. 
Cultures of the principal types found in the exsiccati were studied 
under varied conditions in order to learn something of the constancy 
of the characters which are made the basis of specific distinctions. 
The original generic descriptions were studied in order to ascertain 
the basis of generic distinction. 
The Value of Written Descriptions 
An examination of the specific descriptions of the two genera in 
question showed that spore measurements were most constantly used 
in distinguishing between species; in many cases several species were 
alike in every character given except that of size of spores. In order 
to learn something of the variation in measurements which may be 
due to the personal element and to the use of different micrometers 
and microscopes in measuring, three slides were prepared and together 
with cultures of Phoma destructiva Pat. were sent to a number of persons 
