1897 OBSERVATIONS ON THE MYXOBACTERIACE 493 
spore wall was noticed nor was any further development of the 
' rods by fission seen, although both may have been overlooked. 
Recently, however, by cultivating in Van Tieghem cells the 
spores of JW. rubescens taken from pure agar cultures, I have'repeat- 
edly obtained abundant germinations and have been able to fol- 
low the whole process with a ;, oil immersion. The most 
convenient mode of procedure for this purpose I have found to 
be as follows. A small amount of the spore-material, which is 
easily obtained free from rods when taken from pure agar cul- 
tures, was spread near the center of a sterilized cover glass; 
and when thoroughly dried on, so that the spores adhered firmly, 
was covered with a thin slice of nutrient agar transferred directly 
from the surface of a sterilized agar tube. The coverglass was 
then mounted on the cell in the ordinary fashion, a small amount 
of water containing unicellular algae being added within it to 
furnish moisture and oxygen. The spores were thus firmly fixed 
in definite positions on the under side of the cover and could be 
readily examined directly with the immersion objective. In 
these cultures the germinations began to be visible in from one 
to two weeks, seven days being the shortest period within which 
they occurred; and in all cases they were of a single type, no 
instances being noticed in which the spores underwent the gradual 
change of form above described, which on the assumption that 
NO Separation of the rod from the spore wall occurred, must, I 
think, be considered an abnormal phenomenon. 
The first indication of germination, as shown by prepara- 
tions which, since they could not otherwise be stained, were 
made directly from the Van Tieghem-cell cultures, consists in 
the slight enlargement of the spore and the recovery of its 
POWer quickly to absorb stains. Such deeply stained spores are 
Conspicuous in a field, contrasting with the still refractive and 
wholly colorless ones in which germination has not yet com- 
menced. The walls of the spores thus stained (fg. 34) appear 
as if irregularly corroded by absorption from within, and even- 
tually become comparatively thin, often more so at one or two defi- 
nite points than elsewhere. At such a thin point a protrusion is 
