Book excerpt: Micro-organisms that successfully develop universality of distribution and omnivorousness of habit generally belong to groups characterized by great diversification in appearance, in morphology, and in physiological adaptation. Because of this diversity investigators encounter organisms varying in minor details and describe them as new. Of the fungi that are universally distributed and significant in incipient spoilage of organic products useful to man, members of the Aspergillus glaucus group are among the most important in their action and striking in their habit.