130 James R. Weir. 
often happens that the aecidia and uredomycelia produce a second 
crop of spores. 
The significance of the two kinds of conidia spores has caused 
some discussion. Arthur has suggested that in the aecidium the 
rejuvenescence of the fungus takes place, and in the light of the 
nature of the aecidium as revealed by the investigations of Blackman 
and Christman his point seems well founded. It happens in many 
species that certain of the spore-forms are suppressed, and the life- 
cycle is much simplified. In some cases the uredospores are 
wanting, the aecidium being the repeating generation. In cycles with 
the aecidium suppressed the uredo is the repeating generation. 
When both aecidium and uredo are wanting the teleutospore is the 
repeating generation. A complete life-cycle includes all spore forms, 
the repeating generation being the uredo. 
So much having been said concerning the general characteristics 
of the group we come now to the detailed life-history of a typical 
form. 
A fitting place to begin to trace the life-cycle is with the mature 
teleutospore, as it is here that the transition from one generation to 
the other takes place. On germination each cell of the teleutospore 
gives rise to a four-celled promycelium. The details of this division 
differ greatly in different species. 
In Phragmidium a germ-tube is sent out into which the primary 
fusion nucleus passes. The nucleus by two successive divisions, 
followed in each case by cell-division, gives rise to the four-celled 
promycelium (Blackman, Figs. 8, 9). Coleosporium souchi arvensis 
the teleutospore divides directly to form the four-celled promycelium 
which appears as a four-celled structure with the four internal 
basidia arranged in a chain one above the other (Harper and 
Holden, Fig. 6). In a study of Coleosporium pulsntillce collected on 
Anemone pulsatilla, the details of the division have been observed to 
differ from the above in the internal basidia being arranged in the 
form of a tetrad. This unusual appearance is described in another 
part of this paper. The essential features being, however, in the 
division mentioned above that from the teleutospore a four-celled 
structure is derived, each cell of which bears a single nucleus. From 
each cell of the promycelium a single spore is produced. This 
spore is usually uninucleate, but occasionally the nucleus undergoes 
a division giving rise to a binucleate spore. No cases have been 
reported in which a wall formation follows this division. 
The sporidia on germination give rise to a mycelium the cells 
