2 86 
STRUCTURE AND LIFE HISTORIES 
species possess different colors, but they never possess 
chlorophyll. 
276. Reproduction. At a certain stage of development, 
the plasmodium will begin to form tiny upright stalks, 
at the top of which will develop a spore-case, containing 
spores and capillitium (Fig. 209) . The capillitium consists 
of hygroscopic threads which aid in the dissemination of 
the spores. When the spores are ripe they are scattered 
FIG. 210. Kohlrabi, showing club-root, caused by a myxomycete, 
Plasmodiophora brassicce. (Cf. Fig. 2.) 
by the wind, and each, on germination, produces a swarm- 
spore. A new plasmodium results from the fusion of these 
swarm-spores. 
276. Economic Importance. The Myxomycetes have 
very little economic importance, but the disease of cab- 
bages, kohlrabi, and turnips, known as club-root, is caused 
by a slime -mold growing on the roots (Fig. 210). 
277. Bacteria. The bacteria are among the very 
