36 



A MANUAL OF THE PENICILLIA 



EXUDATE 



Transpiration of fluid is a conspicuous feature of some growing colonies, 

 evident but inconspicuous in others, and wholly lacking in still others. 

 Where transpired fluid, or exudate, accumulates in drops it becomes a 

 conspicuous feature of the growing colony, usually marked by a fairly 

 constant color for a particular species. Sometimes the production of 



Fig. 5. Conspicuously zoiuite colony developed by a white-spored mutant of 

 Fenicillium urticae Bainier, X 18. 



exudate of a general color is characteristic of an entire series, as for ex- 

 ample in the formation of yellow exudate by members of the Penicillium 

 chrysogenum series (fig. 6). In such a ease it aids materially in establish- 

 ing broad relationships. 



Evaporation in older colonies frequently leaves residues upon the sur- 

 face of the conidial area, and may create depressions where conidial masses 

 were pressed do^vn or held aside by the weight or mass of the transpired 

 fluid. These residues and drops must be correctly interpreted else they 



