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healthy seed from abroad, and that he had permission of the late gov- 
ernment authorities for stating that this was the result of their consular 
returns. The unavoidable adoption of this advice increased the disease 
in after years, whether if arose from chemical, structural, or fungoid con- 
ditions. 
If a healthy potato is so dug out on its opposite ends that it will re- 
semble a double egg-cup, and placed erect on one end for about six days 
in an atmosphere at the temperature of 70° F., its under cavity will be- 
come covered with mildew and its fruit will appear in the form of blue 
mold, Penicillium glaucum. In this case the inverted cavity will retain 
the moisture, and as a consequence slight fermentation will ensue, the 
fungus deriving its nutriment from the potato; but the upper surface, 
although fully exposed to the floating’ germs in the atmosphere, will not 
sustain a fungus growth, in consequence of the free evaporation of the 
moisture from it. This form of fermentation should not be confounded 
with that produced by the fungus of potato-rot, Peronospora infestans. 
The chemical action of the blue-mold fungus is slow, and its odor is 
simply that of sour paste, while the destructive action of the potato- 
rot is very rapid, producing a higher state of decomposition and very 
offensive odors. The mycelium and fruit of each fungus also differ essen- 
tially from each other. Both forms of fungus produce oxidation, but with 
very different results. Consequently potato-rot consists of more than the 
mere ‘decay of the tissue by its absorption of oxygen.”’ The purely 
fungoid theory, on the other hand, will not account for the many excep- 
tions pointed out by those who favor the chemical theory; since it may 
be shown that as the chemical constitution and density of any vegeta- 
ble vary, so will the genus and species of fungi be found to vary with 
the proximate principles of plants. 
The following case of rust on the Kittatinny blackberry illustrates 
forcibly the fact that the structural and chemical condition of a living 
plant shonld always be considered in relation to fungus growth on 
them. 
Chalkley Gillingham, of Accotink, Fairfax County, Virginia, under date 
of Secondmonth 28, 1873, describing the condition of his blackberry 
canes during the spring of 1872, says that six years ago he planted ten 
rows of Kittatinny and ten of Wilson in the following manner: First, 
four rows of Kittatinny, then following, alternately, Wilson and Kitta- 
tinny, six rows of each, ending with four rows of Wilson. All had been 
treated alike from the time they had been received by him, and all ap- 
peared healthy until last spring, when the Kittatinny became covered 
_ with “rust.” Ata short distance the rows of Kittatinny appeared as 
if painted with yellow ocher. Some were destroyed from its eftects. 
None of the Kittatinny canes bore fruit. The Wilson were uninjured, 
although surrounded by an atmosphere laden with fungus spores. 
Every leaf of the Kittatinny was covered with hundreds of millions of 
spores, yet not a leaf of the Wilson was affected. The Wilson canes 
bore the usual complement of fruit. Mr. Gillingham states that the 
canes have not been manured for several years. 
The glossy covering of fruits and lefves consists of wax, that of the 
grasses of siliceous matter. The wax may be removed by sulphuric 
ether, the siliceous matter by caustic alkalies or hydrofluoric acid. 
Should plants fail to eliminate and cover their surfaces with wax or sil- 
ica for their protection, their albuminous substances will then afford food 
for the growth of fungi. Futureinvestigations may prove that in the 
case of the Kittatinny blackberry alluded to, the absence of this outer pro- 
tection was thecause of their destruction. The accompanying illustration 
