14 
Hogg, on Vegetable Parasites. 
by parasitic growth; therefore I still believe that an 
eruptive condition or an abraded secreting surface is a very 
necessary part of the disease^ and that then the skin affords 
a more particularly favorable soil for the development of the 
fungus ; but leaving this part of the subject for the present, 
I shall proceed to show in an experimental and, I trust, a 
satisfactory way that the same species of fungus often 
exhibits varieties of character, as well as form, at different 
stages of development and under varied influences ; so much 
so, " that neither size nor outline affords any basis for dis- 
tinction into species until it has been ascertained, from ex- 
tensive comparison of forms brought from different localities 
in the widest area over w^hich the species can be traced, what 
are the average characters of the type, and what their range 
of variation/^ (Bentham.) 
First, with regard to collecting and taking fungi, I find 
that the prevalence of damp or moist close weather is espe- 
cially favorable for the purpose; while in an opposite 
condition of the atmosphere — fine frosty wreath er — I have 
rarely been able to secure a supply ; and, moreover, my ex- 
perience has proved to me that in the winter season diseases 
of the skin accompanied by parasitic growths disappear from 
among the poor who frequent our skin infirmaries. Mr. 
Hunt also finds that season brings with it its own peculiar 
type of skin disease. 
It appears that at particular periods of the year the atmo- 
sphere is, so to speak, more fully charged with microscopical 
atoms than it is at others. The spores of the moulds, 
aspergilli, penicillia, and puccinia, are perhaps the most widely 
distributed bodies, and towards the end of the hot weather, 
or about autumn time, they are very abundant. Among those 
who have taken them at this period of the year we must ever 
associate the name of one of our body, the Hev. Lord 
Godolpin Osborne, who, I believe, first experimented in this 
way during the cholera visitation of 1858. He exposed pre- 
pared slips of glass, slightly moistened with glycerine, over 
cesspools, gully-holes, &c., near the dwellings of those where 
the disease appeared, and caught what he named aerozoa — ■ 
chiefly minute germs and spores of fungi. I was favoured 
with a few specimens, one of which I have placed under a 
microscope on the table for the purpose of comparison with 
the more recent specimens taken by myself two months ago ; 
a drawing made from this (see Plate V, fig. 4) exhibits spores 
almost identical with those found in the skin, &c. 
From the year 1858 to the present time I have amused 
myself by catching these floating atoms, and, so far as I can 
