144 THE AMERICAN MONTHLY [May 



other plants. They are true parasites, occurring on liv- 

 ing leaves, and are characterized by a great development 

 of spores in proportion to the vegetative portion or my- 

 celium, and were formerly called Coniomycetes, or Dust- 

 fungi, for this reason. .As examples, we may take Phrag- 

 midium bulbosum (rubi), which is exceedingly common 

 on the bramble in summer and autumn, and forms little 

 sooty patches on the under side of the leaf. Under the 

 microscope it is seen to consist of oblong bodies divided 

 into four or five sections, and having a kind of handle at 

 one end ; these are the "teleutospores." Mixed with the 

 teleutospores will probably he some globose warted yel- 

 low bodies, formerly placed in a separate genus (Lecy- 

 thea), but now known to be only another stage of the 

 Phragmidium, and called uredo- (or brand) spores. Other 

 species occur on roses — often doing them much injury — 

 on raspberry, barren strawberry, etc. 



In the closely-allied genus, Puccinia, which forms the 

 rust of wheat, and of which other species are found on a 

 great variety of wild and cultivated plants, the teleuto- 

 spore has only two compartments, and in addition to the 

 uredo-spores which occur on the same plant as the teleu- 

 tospores — usually earlier in the season — a third form of 

 fructification is met with in many cases, which is so un- 

 like the Puccinia that it was placed in a separate order 

 and genus, called jEcidiu7n, popularly Cluster Cups. 

 These are generally found on entirely different kinds of 

 plants from the Puccinia, and form groups of tiny cups, 

 usually yellow or white, with fringed margins and yellow 

 spores within. They are now described as the "{Bcidio- 

 spores" of the Puccinia. One of the commonest is that 

 found on leaves and fruits of the gooseberry ; in the for- 

 mer the leaf is red above, and the cluster of cups beneath 

 yellow, forming a very pretty low-power object for the 

 microscope. We have thus a most remarkable alterna- 

 tion of generations, for' the spores of the berberry 



