90 
CHARLES THOM AND MARGARET B. CHURCH 
single mixtures of primary colors. The young culture may first show 
color as one Of the paler tints of a series, then become successively 
deeper, and not infrequently in age change to some one of the darker 
shades of the same series. A change in the primary mixture fre- 
quently develops in the same colony with age. Such changes with 
rare exceptions bring combinations closely related to the original, 
such as are found in adjacent columns or upon the same page in 
Ridgway. 
An organism showing one of these colors must, therefore, be 
critically compared in all its characters with those described as show- 
ing any of the related colors. In making this comparison these 
descriptions have been brought together and considered. Before de- 
scribing A. terreus as new the original descriptions of this series were 
examined in every case and frequently all references in the literature 
were followed. The original citations have been included in the 
synopsis of the group presented and where possible an opinion is given 
upon the proper placing of the form. 
In habit and colony appearance A. terreus, A. fumigatus and A. 
nidulans resemble each other more closely than they resemble such 
forms as A. niger, A. ochraceus or A. flavus. They may, therefore, 
be taken as typical forms in three related series. A brief review 
of the history of the two series of forms typified by A. fumigatus of 
Fresenius^^ and A . nidulans of Eidam^^ will be followed by a synoptical 
presentation of the whole group as far as the material could be inter- 
preted. 
Aspergillus fumigatus Series 
A. fumigatus was described by Fresenius in 1850. References to 
molds in the human ear go some years farther back, but no previous 
author gives an adequate description of the form. The figures of 
Fresenius fix a type of conidiophore and fruiting head which is readily 
found by examination of cultures today. However, since organisms 
with this morphology are found everywhere and upon a wide variety 
of substrata, the student of comparative cultures soon finds strains 
with this conidial morphology but cultural characters diverging fairly 
widely and apparently fairly stable. It is not surprising to find 
12 Fresenius, J. B. G. W. Beitrage zur Mykologie. P. 81, pi. 10, figs. i-ii. 
Frankfurt. 1850. 
^2 Eidam, E. Zur Kenntniss der Entwickelung der Ascomyceten. Cohn's 
Beitr. Biol. Pflanzen 3: 377. PL 21, 22. 1879. 
