330 FIRST FORMS OF VEGETATION. 
devitalized by other noxious influences, such as 
vitiated air, defective sewerage, bad water, or an 
inadequate supply of food, and consequently in a 
state of body unable to resist the deleterious ac- 
tion of these cryptogamic germs, died from a form 
of poisoning. These countless myriads, then, of 
invisible seeds which continually float in our at- 
mosphere, ever ready to alight and spring into 
life, as the advanced heralds of the plague and the 
pestilence, may well strike us with astonishment, 
if not with awe. Aboveus, about us, and in us, 
they roam like vigilant spirits, seeing that all is 
right with our physical constitution ; but availing 
themselves of the slightest flaw to work our 
destruction. 
Although fungi are in an especial manner cap- 
able of universal dissemination, yet we find that in 
their geographical distribution they are as much 
restricted as other plants. Some representatives 
of the class are found in every part of the world, 
and some particular species have the power of in- 
definite extension and localization, but, as a whole, 
like the higher cryptogams, they can only spread 
within certain limited areas. The habits of fungi 
convince us that there is something apparently 
capricious in their distribution, or rather, that 
some only of the conditions upon which their mul- 
tiplication depends are at present known, In 
