396 | The Botanical Gazette. [December, 
behind as a distinct shining membrane in which a few rods 
remain here and there imbedded. 
The duration of the vegetative period varies according to cir- 
cumstances. In artificial cultures it usually lasts about a 
week or even two weeks; but in nature the production of cysts 
must certainly be more rapid. In Chondromyces lichenicolus, 
for example, a period of moist weather following continued 
drought, and lasting not more than two or three days is suf- 
ficient to cover the previously dry tree trunks on which it 
vegetates with large patches of cysts. ji 
he preparations for the production of cysts are apparent 
to the naked eye in artificial cultures of C. crocatus, for exam- 
ple, about a day before the cystophores begin to rise. In this 
condition the colony even in the neighborhood of its advanc- 
ing edge, assumes a lumpy appearance owing to the aggrega- 
tion of rods at various points. In forms like Myxococcus, in 
which the rods are somewhat scattered, the first preparation 
for spore production as seen under the microscope consists in 
the appearance of groups of rods moving with a circular ten- 
dency and forming whirlpools, so to speak, in which the more 
central individuals soon become converted into spores, the 
successive formation of which results in the production of the 
elevated spore masses characteristic of the various forms. 
The formation of a cystophore where it occurs results from 
the basal constriction of a papillate mass of rods which pro- 
jects from the surface of the colony. The mass of rods mov- 
ing upwards on one another, continually leaves behind and 
below it an external layer at its base which has become 
slightly hardened by exposure to the air and is composed 
partly of the gelatinous matrix, partly of individuals which 
soon become indistinguishablein it. As the mass rises within 
and above this slightly hardened layer, the latter, while being 
constantly renewed above, becomes contracted below to form 
the cystophore. The cystophore may therefore be compared 
during its formation, to a glass funnel, the flaring portion of 
which is being constantly renewed from the outer surface of 
the mass of rods contained within and rising above it, while 
the tubular portion is being constantly lengthened by the con- 
traction of the flaring portion at its base. As the freely 
Moving individuals pass up out of the upper portion of this 
tube it is left behind as a gelatinous structure which becomes 
