88 
GROWTH OF TIIE FUNGUS. 
The outcome of all this may be summed up as follows : When the 
spore is allowed to germinate in water the tough outer skin bursts, and 
a thin hyaline cellulose membrane inclosing the swelling protoplasmic 
contents emerges as a delicate tube. In some cases this tube protrudes 
through a definite thin spot; in others no germination could be induced 
in water, even though plenty of air was present and the temperature 
normal. The older the spore the longer the time required before germi¬ 
nation. 
When the above germinal tube has attained a length of, say five or 
six times the diameter of the spore, it breaks up into segments, and be¬ 
gins to put out numerous bud-like branches, which soon separate as 
single cells, looking very like cells of the yeast plant. These yeast¬ 
like cells have usually been called sporidia. In some species the spo- 
ridia are long and thread-like, and are produced in a sort of coronet. 
Other varieties in detail occur, but our purpose is served if the reader 
apprehends that the usual mode of germination in water is for the spore 
to put forth a short tube (the so-called pro-inycelium), from which sev¬ 
eral sporidia are then budded off. 
**###*# 
HOW AND WHERE THE FUNGUS ENTERS THE PLANT. 
The first steps in the elucidation of the extremely difficult problems 
here involved were taken by Hoffman, Kuhn, and Wolff during the 
period between I860 and 1880. Kiihn was the first, I believe, to actu¬ 
ally perceive the penetration of the fungus into the plant. He showed 
that if the spores of the bunt fungus ( Tilletia) are sown with the wheat 
grains they germinate and produce their promycelia pari passu with 
the emergence of the radicle of the young wheat seedling; from the pro¬ 
mycelia are developed the now well known sporidia, and these sporidia 
then put forth extremely fine fungous filaments, which x^enetrate the 
young and delicate tissues of the embryo wheat plant, somewhere in the 
part (collar) common to root and shoot. Kiihn repeated his experiments 
successfully with the smut of corn, and with several other species, al¬ 
ways finding the incipient mycelium of the fungus in the delicate col¬ 
lar. After some years of research Kiihn concluded that the normal 
mode of infection common to the majority of these fungi is the following: 
The spores ripen in the smutted and bunted cereals with the grain, and 
are garnered with the latter; they become scattered on the healthy 
grains, and may be sown in the following spring with these. As the 
young cereal germinates, the attached spores produce their promycelia 
and sporidia, and the germ-tubes from the latter penetrate the embryo 
corn plant. But now came the crux. If the fungus is such a virulent 
parasite as it was made out to be, how is it that we see little or no more 
of its effects until the late summer and autumn, when the grain begins 
