39 
A Microscopical Inquiry into the Vegetable Parasites 
infesting the Human Skin. By Jabez Hogg, M.E.C.S.E., 
&c. 
(Eead Jan. 26ih, 1859.) 
An investigation into the many peculiarities whicli sur- 
round parasitic growths^ and their rapid development and 
increase^ is one that may be expected to repay the micro- 
scopist for any amount of time he may bestow upon them, 
and we find, indeed, as much to interest and instruct us, in 
this the lowest department of vegetable life, as in that of the 
highest. The microscope shows us that all the fungi have 
seed-vessels bearing fruit a hundred or a thousand fold, and 
that there is scarcely a spot of earth on which this fruit in 
the shape of minute spores cannot be found. Insoluble in 
nature, they wait, where they fall, the growth and decay of 
the particular plant for which each has its affinity ; so that 
the enemy is near to the very soil from which it is to draw 
life. These spores, so imponderable, float about in the air 
we breathe, seeking a nidus in everything, be it vegetable or 
animal. In the latter, whenever the healthy processes of 
nutrition are impaired, and the incessant changes between 
the solids and the fluids slacken, the human skin then fur- 
nishes a rich and proper soil for these spores to take root in 
and germinate. I have lately been engaged in a micro- 
scopical examination of the products of the cutaneous surface, 
for the purpose of ascertaining what share the parasitic 
growths take in the production of certain well-known forms 
of skin disease, and to decide, if possible, whether they are 
directly and solely the cause of disease and disorganization 
of the epidermal structures ; or whether, from a decline of 
the general health, or some constitutional predisposition, the 
parasitic vegetation is the result of disease ? 
For the elucidation of my subject, I have made in all up- 
wards of eighty examinations of the products of skin dis- 
eases, taken from patients under my friend Mr. Hunt^s care 
at the Western Dispensary for Diseases of the Skin. The 
products have been examined wet and dry, with reflected 
and transmitted light, under a power of from 200 to 400 
diameters, and every means taken to avoid error. The spe- 
cimens have been obtained in scaly and papulous diseases by 
gently removing the half-detached scales ; in moist eruptions, 
by simply placing the discharge on a slip of glass ; in diseases 
of the hairy scalp and beard, by uprooting the hairs and ex- 
amining them immediately. The sketches were made at the 
same time pimply with a view to a faithful portraiture of what 
