Thom: Penicillium Luteum-Purpurogenum Group 139 
from the base upward for 5 to 8/t, then taper slowly to the di- 
ameter of the conidium producing tubed® with a total length of 
from 10 to 15 fi,. The length of these cells, their lanceolate or 
lance-acuminate form and closely parallel arrangement is charac- 
teristic for the whole group. 
CONIDIA 
The conidia arise as cylindrical cells which change usually 
through fusiform to elliptical or in some cases almost globose, 
with walls, when fully ripe, either smooth or delicately rough- 
ened, or sometimes both in the same culture. The fusiform to 
elliptical shapes are most common. Variation in size in the same 
strain and usually in the same culture is very marked. Even 
strains with conidia averaging small have some which reach the 
sizes shown by the larger spored forms. Very large single 
spores and chains of spores are abundant in some strains while 
rare, or perhaps absent in others. In forms where the conidia 
have been germinated under observation the conidia swell to these 
large sizes while germinating. Masses of conidia where present 
give some shade of green to that part of the colony. 
It is, therefore, possible to bring this group together in such a 
way as to aid the worker in locating the strains found. Whether 
any one can so define the appearances of each of the separate 
strains as to ensure identification by others is doubtful. Perhaps 
for most purposes it is immaterial. 
A synoptical arrangement of the strains considered in this 
paper has been prepared from cultures grown in Czapek’s solution 
agar.^® When incubated at 37° C. five strains failed to grow, 
namely. Nos. 2647, 3525.15, 3523.47, 2751, and 4010.9. The 
other strains grew well at blood heat. The cultures which failed 
15 Thom, C. Conidium production in Penicillium. Mycologia 6 (1914) No. 
4. pp. 211-215. 
Distilled water 
1,000 c,c. 
Magnesium sulphate 
0 
Dipotassium phosphate (K2HPO4) 
I.O “ 
Potassium chloride 
0-5 
Ferrous sulphate 
Cane sugar 
30.00 grams 
Agar 
