120 Transactions British Mycological Society. 
5. Contdia. 
As mentioned above, the conidia in artificial cultures. differ 
considerably from those formed in nature. Upon vegetable 
debris in nature, the conidia are almost entirely of the large - 
variety, while in cultures the large conidia are masked by the 
enormous numbers of small conidia formed by the process of 
budding described above. In culture, the conidia are in long 
branched chains, forming a more or less dense head at the end 
of the conidiophore. The number and length of these chains of 
small conidia is an index of the amount of budding that has 
taken place, and has a marked effect on the appearance of the 
conidiophore as seen intact under the microscope. In some 
strains, as S, the conidiophore terminates in a dense mass of 
chains of small conidia, while in other strains, as Z, the process 
of budding is much restricted, the conidiophore being terminated 
only by a small head of conidia. The budding influences the 
percentage of large conidia present, this being much greater 
in Z than in S. 
The conidia vary greatly in size, from small spherical spores 
of about 4p in diameter, to large cylindrical conidia up to 
25 x 4-5p. The large basal conidia of the “head” merge 
gradually into the small spherical conidia of the distal parts of 
the chains. The large conidia are more or less cylindrical, 
tapering slightly at the ends, and may be 1-3 times septate, 
* the septation being more frequent in old cultures. 
According to Saccardo(:s) and Rabenhorst(14) the large 
conidia of C. herbarum are constricted at the septa, but while 
this constriction is common in nature, though by no means 
universal, it is exceptional in artificial cultures, and is not 
characteristic of any particular strain. The same authors state 
that the walls of the conidia of a form (Vincetoxict) of C. her- 
barum are granular to echinulate, but in our cultures indications 
of a roughness of the conidial walls were very rare, although 
the walls of the conidia originally formed in nature by some 
strains were certainly rough. 
The colour of the conidia as seen under the microscope varies 
with their age, the largest (i.e. also the oldest) conidia being 
darker in colour than the small conidia of the distal ends of the 
chains. In some strains, as Z, the conidia never become very 
dark in colour, while in S they become almost black. Every 
intermediate between these two extremes is present. 
A minor point of difference between the two extreme strains 
S and Z is that the latter never formed truly spherical spores, 
while in S the fourth or fifth conidium from the base of the 
“head” was practically spherical. 
