258 D. D. CUNNINGHAM. 
phenomenon is specially marked in reference to the sporangioid 
bodies and P2dodolus, which, as we have already seen, are the 
Fic. 10.—Slender Bacterium common in cow dung X 1000. 
first forms which make their appearance. Crops of sporangia 
are rarely produced for more than two or, at utmost, three 
days, and crops of Pz/obo/us for more than six or seven, and in 
this case it is only for two or three that the development is 
abundant. We have an enormous primary production of repro- 
ductive bodies and an absolute, or almost absolute, failure of 
any further development due to these. Where the primary crop 
has been abundant, it is very questionable whether the repro- 
ductive elements then produced ever germinate in the same 
medium in which they were produced; for although, as before 
said, successive crops of fructification appear for two or three 
days, these apparently all belong to one generation. This cer- 
tainly is the case in so far as Pilobolus is concerned; there is 
no evidence of successive generations of mycelia, and the suc- 
cessive crops of fruit are in many cases visibly the result of 
unequal rapidity in the development occurring in basal diluta- 
tions contemporaneously developed. The phenomenon is clearly 
one of exhaustion of the nutritive basis, and not due to defec- 
tive germinal energy or the reproductive elements ; for we have 
only to transfer some of them to a suitable fresh basis to secure 
their immediate development. While in the primary basis we 
find the surface covered with masses of reproductive elements 
totally incapable of farther development, so long as they remain 
there, we have only to transfer a few of them to an unexhausted 
