UREDOSPORES 33 
This would be the case in a true Hemipuccinia, but none of 
these have so far been cytologically investigated. 
Uredospores are always unicellular, except in the case of 
a few monstrosities. Primarily they must be considered a 
device to aid in rapid propagation and hence may be called 
summer-spores: for this reason they usually germinate with 
great readiness when mature, always forming a tube which 
enters a stoma of the host. The number of germ-pores varies 
from 1 to 10 (usually 2 to 4): only one case is known in 
Uromyces where they possess a single pore (U. uniporulus) and 
one in Puccinia (P. monopora). They present a wonderful 
sameness in shape throughout the whole group, and in colour 
vary from yellow and orange to brown. It may be taken as 
a general rule that if the wall is colourless, the contents are 
yellow or orange from an abundance of that yellow oily 
substance which occurs in ecidiospores ; if the wall is distinctly 
brown, the contents are often colourless when mature, though 
at first they frequently contain the usual yellow oil. It is only 
in a few. instances, in the lowest genera, that uredospores are 
quite without colour. The uredospores of Puccinia dispersa 
and in a smaller degree of P. graminis are noticeable for a 
curiously dull appearance which is very characteristic, because 
they combine orange contents with a brownish membrane. 
The outer wall of uredospores is almost always covered with 
spines (echinulate), needles (aculeate) or warts (verruculose) ; 
it is very rarely smooth; these projections enable them to cling 
more readily to the surface of the host. They are often inter- 
mixed with paraphyses, which are usually clavate or capitate 
in shape; these are found in a few species of Puccinia, but 
more especially in Melampsora and Phragmidiwm. These 
paraphyses are homologous with the spores, being binucleate 
at first, but the nuclei soon disintegrate. 
There is very frequently found, in the uredo-sori of many 
species a parasite belonging to the Deuteromycetes, called 
Darluca Filum. It consists of a black pyecnidium, enclosing 
numerous uniseptate pycnospores which are faintly apiculate: 
at each end. This has been sometimes mistaken for another 
spore form of the Uredine. 
G. U. 3 
