THE SMALLER FUNGI. 629 
of facts, respecting what have been considered as three or 
more genera of the smaller and parasitical fungi. The ac- 
count is in effect the epitome of De Bary’s experiments, as 
given in the “Annales des Sciences Naturelles, Series 4, Vol. 
20.” Starting from Uromyces, we successively arrive at 
Acidium or cluster-cups, and Uredo or Rust which, though 
found in some one of these stages on particular living plants, 
in reality belong to the development of one and the same 
parasite. Should any doubt arise as to the validity of these 
conclusions, the microscope and the too common occurrence 
of the several kinds or conditions afford facility for question 
and investigation. A study of similar stages of development 
by my friend Henry F. King, long ago interested me in the 
subject, and I here would bear grateful and willing testimony 
to his patience and skill in microscopical Fig. 2. 
studies pertaining to the structure of the 
vegetable kingdom, and of its lower orders 
in particular. 
The couch grass, or twitch grass ( Triticum 
repens), is a well known weed, and though 
recommended for its nutritive qualities, is 
seldom cultivated unless in very light and 
dry soils. But with a pertinacity worthy a 
better fate, it springs up spontaneously in 
neglected spots, and can be found almost 
anywhere. Whoever is familiar with it, must 
-have noticed that its broad leaves and stout 
stalks are frequently variegated and dis- 
colored by linear marks of a dusky hue, 
Which on nearer inspection prove to be veritable cracks of the 
skin, from which protrude clusters of minute dusty particles. 
This diseased state is owing to a parasitic fungus, the Puc- 
cinia graminis, or the Rust, which sometimes does incalcu- 
lable injury to grain crops. Many other plants are infested 
with the Puccinia Rust (Fig. 2; 4, wheat-straw attacked by 
mildew, Puccinia graminis; b, cluster of spores of corn 

