104 



THE FUNGI IMPERFECTI AND THE ASCOMYCETES 



branching occur. The asymmetrical forms make up the fourth group, 

 the Asymmetrica. This classification can be more readily under- 

 stood from a diagram than from descriptions (Fig. 51). These char- 



iStcpigmata- 

 Metulae 



Mono- Bi- Poiy- 



VGPticillat'a 



V . - 



Y ' 



5(jmmatTica AscjmmGtnca 



Fig. 51. Diagram illustrating the different t3^pes of spore heads of Penicillia. 



acters are subject to some variation, even in a single culture, but a 

 dominant tendency will be manifest, 



Monoverticillata. Certain molds which formerly were classed as 

 a separate genus, Citromyces, fall in this group. The name was 



Fig. 52. Penicillia from fruits: a, Penicillium expansum; h, P. italicum; c, 



P. digitatum. 



given (by Wehmer) to two species producing citric acid from sugar. 

 These forms were first considered as occupying a position transitional 

 between Aspergillus and Penicillium, since some strains showed a 



