HoGG^ on Parasilic Fungi. 
53 
carefully selected well-marked cases only for microscopical 
examination. 
Lastly, as to the growth of these parasites on the healthy 
skin; most conclusive experiments have been made, which 
go far to prove that the skin of persons in health and vigour 
does not afford the required conditions for their taking root 
in it ; that inoculation succeeds in those places only where 
pustules have previously formed. Remak and others tried 
the experiment of inoculation over and over again, but found 
it always failed in the healthy ; yet in certain exudations or 
peculiar states of the constitution, or where disintegrated 
matters existed, and which had undergone particular che- 
mical changes, the Achorion may be made to germinate and 
produce growths of these identical fungi. 
Remak took the spores of fresh scabs, and found he could 
grow them on slices of apple. After twenty-four hours, 
the sporidia exhibited short, pale, homogeneous, cylindrical 
growths, which became larger and more transparent during 
the following interval. Small oval cavities were observed 
on the third and fourth days on the outgrowths, not sepa- 
rated by partition-walls, which increased in size ; and on the 
sixth day a luxuriant growth of the Penicillum glaucum, or 
other species of mould, entirely covered the Favus fungus ; 
and further observation could not be made. Perhaps their 
development was arrested by the decomposition of the masses 
of fungi, owing to the chemical alteration of the soil. 
The spores of the Favus fungus germinate in solutions of 
sugar, but produce only thallus threads; the sporidia are 
formed when it is exposed to the action of the atmosphere. 
The mass of scabs crumbles in distilled water without ger- 
minating. The spores do not germinate in blood serum, or 
the solution of the white of egg, or in animal fats ; but this 
was speedily effected when sugar was added, or a solution 
poured over either of them, when mildew grew rapidly over the 
Achorion, just as other mould spores quickly germinate on 
decaying fruits, &c. These experiments closely connect and 
identify these fungi with the vegetable-growing species, and 
from which they do not appear to me to differ in their most 
essential characteristics. 
Seeing then that the fungi are characterised throughout 
nature by feeding on effete or decayed matter, that the fungi 
supposed to be peculiar to certain diseases of the skin are 
also found in many other diseases of the cutaneous surface, 
that competent observers have not been able to find them in 
these peculiar diseases, that sporules and filaments described 
as the cause of one specific disease have been found in the 
products of another definite disease inferred to have a 
