LS = US : 
SECTION OF VEGETABLE PATHOLOGY. 345 
thickens and pushes out lateral or side branches from the swollen 
points. 
: A number of experiments have been made jin the laboratory in 
germinating the spores of Fusicladium in various solutions and at 
different temperatures. It was found that they germinated most 
readily in pure water at a temperature of about 50° F., the time re- 
quired usually being about eight hours. In thirty hours the germ 
tubes attained a length many times that of the spore. Under certain 
conditions, not well understood, the filaments developed secondary 
spores at their tips, and these in turn germinated like the original 
spore. 
even subjected to a comparatively high degree of temperature, 
and all water removed, growth in the germinating spores ceased, but 
was renewed at once upon being restored to the favoring conditions 
of heat and moisture, even after the lapse of four or five days. 
Repeated sowings of the spores made in solutions of sulphate of 
copper of various strengths, showed that a one-fourth of 1 percent. 
solution would effectually prevent germination; in a one-eighth of 1 
per cent. solution about 10 per cent. of the spores germinated, but 
they made only a feeble growth. 
In the study of the diseased White Winter Pearmain, mentioned 
above, there was unmistakable evidence of the penetration of the cuti- 
cle by the germ tubes. As an experiment, some germinating spores 
were sown on the healthy surface of one of the apples and then kept 
moist under a bell-jar. In ten days it was found that the germ tubes 
had penetrated the cuticle in several places, and made a considerable 
growth in the cells of the epidermis. This penetration was evidently 
effected by a dissolving or eating away of the cuticle through some 
corrosive action on the part of the germ tubes. The possibility of 
infection of healthy fruit from that which is diseased in the same 
barrel thus appears to be evident. 
This reproduction by the spores, joined with the independent 
growths which may arise from the individual cells of the plant body, 
afford ample provision for the propagation of the fungus. No other 
form of this fungus is known than that which we see in the ‘‘ scab” 
of the fruit or “‘mildew” of the leaf, nor does any other form seem 
to be necessary for the continued existence of the species. The fun- 
gus is doubtless perennial, living on the fallen leaves, but more es- 
pecially on the fruit and young shoots during the winter, and the 
low temperature at which the spore-formation takes place, insures its 
early propagation and dissemination in the spring. 
(f) TREATMENT. 
The fungus of the Apple Scab does not penetrate into the tissues of 
the host, and very early in its development it is wholly exposed to 
any application which may be made to destroy it. It appears, how- 
ever, that the vegetative portion or plant body of this, as well as of 
many other fungi, is very resistant to the action of chemical re-agents 
quite as much or more so than are the tissues of the leaf or apple upon 
which it grows. We can scarcely hope, therefore, to accomplish its 
destruction, unless it be the growths infesting the young shoots and the 
scales of buds. Before the latter expand in the spring much stronger 
solutions can be applied than it is possible to use later in the season, 
ana it is at this period that the warfare against this fungus should 
begin. It hasbeen observed that the germination of the spores is 
