MONOVERTICILLATA 189 



and reported that a low acidity favored the formation of the former, 

 ■whereas a high acidity favored formation of the latter acid. Chrzaszcz 

 and Tiukow (1929) investigated citric acid formation by forty-six species 

 of Penicillia, including strains of C. glaher and C. pfeffcrianus, and reported 

 citric acid to be produced by all but three, with the quantity largely de- 

 pendent upon the species. Particular attention was devoted in later 

 papers to the production of acid by a strain designated Penicillium "X", 

 n. sp., and referred to as a citric acid producing organism belonging in the 

 section Aspergilloides, but was not otherwise identified. Mechanisms 

 for the production of citric acid by mold fermentations were proposed by 

 Chrzaszcz and Tiukow, in 1930 and 1932. Oxalic acid production by 

 Penicillium "X" was also investigated by these authors (1930a). Filoso- 

 fov and Alalinovskii (1928) reported Citromyces to produce citric acid 

 equal to 17.1 percent of the sugar in the substrate in 20 days. Frey (1931) 

 compared citric acid production in Aspergillus niger and C. glaher, and 

 found the fermentation by the latter to be adversely affected by pH 2.0 

 produced by mineral acids, whereas J.. 7iiger was not so inhibited. Birkin- 

 shaw and Raistrick (1931) reported certain strains of P. spimdosum to 

 produce good yields of citric acid. 



Penicillium lividum Series 

 Outstanding Characters 



Colonies usually appearing deeply velvety to lanose, consisting of a tough 



basal felt having abundant conidial structures, with conidia in definite 



blue-green shades. 

 Conidiophores typically erect or ascending, long, usually unbranched 



with walls often finely roughened and with apices somewhat enlarged. 

 Penicilli strictly monoverticillate with sterigmata usually crowded in the 



verticil, parallel or somewhat divergent. 

 Conidia elliptical to subglobose, mostly 3.0 to 4.0m in long axis, Avith walls 



echinulate, often conspicuously so. 



Series Key 



1" . Colonies deeply lanose, conidiophores 400 to 500m or more in length, reverse un- 

 colored or in fairly light shades, 

 aaa. Conidia broadly elliptical to ovate, conspicuously roughened 



P. lividum Westling 

 bbb. Conidia narrowly elliptical with ends pointed, delicately roughened 



P. aurantio-violaceum Biourge 



2". Colonies not deeply lanose, conidiophores comparatively short, reverse in deep 



violet to violet-black shades, conidia spinulose P. trzebinskii Zaleski 



Members of this series represent a normal component of the mycoflora 

 of most soils, but occur less frequently than most of the other recognized 



