32 A MANUAL OF THE ASPERGILLI 



Brefeld used decoctions of horse dung variously diluted and stiffened with 

 gelatin. Much of the European work was done with brewery wort; Maze 

 (personal communication, 1904) used extract of white beans; potato and 

 carrot decoctions have been widely used; Bainier grew his molds and de- 

 scribed many of them upon sticks of licorice root; others preferred plugs of 

 potato or of carrot, string beans, etc. The primary aim was to obtain an 

 optimum growth of the mold under observation, rather than to analyze its 

 relation to the substratum or furnish comparative data to distinguish it 

 from other members of a series. 



An optimum culture substratum for comparative study of the Aspergilli 

 needs to contain the necessary chemical elements in the form of pure but 

 assimilable salts, supplemented by carbohydrates of such structure as to be 

 available to the largest number of species, and purchasable in pure form in 

 the chemical trade. Supplementary and often very important information 

 must be sought from variations in the proportions of nutrients used, or in 

 the introduction of widely different substances in replacement of particular 

 components of media already used. The Aspergilli as they are isolated from 

 nature are not very dependent upon vitamins or growth-promoting sub- 

 stances. For cultivation upon solid substrata, agar is almost universally 

 employed as a gelling agent. 



When the study of a large number of molds is undertaken, comparison of 

 these molds under controlled and reproducible conditions of growth become 

 essential. Foremost among the conditions which must be standardized is 

 the culture medium, or substratum. Various authors have proposed 

 standardized and reproducible formulae which in their experience have pro- 

 vided uniform cultures over long periods, hence are of value for comparative 

 studies. A series of such media are presented. 



Czapek's Solution Agar 



As a routine medium for comparative work, the following formula origi- 

 nally adapted from Czapek (1902, 1903) by Dox (1910) has been widely 

 used. Minor variations in quantities apparently do not affect the reactions. 

 Cultural information given in this manual is obtained from growth upon media 

 produced by this formula unless otherwise specified. 



Czapek's solution ar;ar: 



Water 1 , 000 cc . 



NaN0 3 3.0 grams 



K 2 HP0 4 1.0 gram 



MgS0 4 -7H 2 0.5 gram 



KC1 0.5 gram 



FeS(V7H 2 0.01 gram 



Sucrose (Cube or other good commercial grade) 30.0 grams 



Agar 15.0 grams 



