42 Blackman and Fraser . — Further Studies on the 
term basidia of the older workers is no longer applicable, they may 
simply be termed the basal cells of the aecidium, since they are the cells at 
the base of the special cell-rows. 
PUCCINIA MALVACEARUM, Mont. 
As is well known this parasite is one of the lepto- forms, i. e. there 
is only one kind of spore, the teleutospore, and this germinates in the 
sorus immediately on reaching maturity. The whole life-cycle is thus 
completed in a very short time, the teleutospore sorus beginning to appear 
about twelve days after infection. 
As stated by Sapin-Troufify the vegetative mycelium contains single 
nuclei. The first indication of the formation of a teleutospore sorus is 
the development of a tangled mass of uninucleate-celled hyphae, which 
is often more regular towards its edge (Fig. 19). Then directly on this 
mass hyphae with conjugate nuclei arise, and these usually produce an 
irregular mass of binucleate hyphae, on which arise the special cells 
that are later to give origin directly to the teleutospores (Fig. 20). These 
special cells produce one or more teleutospores (Figs. 21 and 22), and are 
very similar, though smaller in size, to the special cells described in an 
earlier paper for Gymnosporangium clavariaeforme. 
Very careful search failed to reveal the exact method by which 
the transition from the single to the conjugate nuclear condition is brought 
about. The smallness of the cells and nuclei, and the absence of any 
regular row or group of cells — such as are found in the aecidia — on 
which attention can be concentrated in the hunt for nuclear migrations 
or cell-fusions, render the task of elucidating such a point almost 
hopeless. That the change of nuclear condition takes place at several 
different points in connexion with each sorus, and not once for all, is 
indicated by the general distribution of the binucleate hyphae which 
first appear. 
Whether the conjugate condition of the nuclei is the result of either 
of the processes observed in the aecidium, or whether there is a still simpler 
process in which two sister nuclei themselves become conjugate in a cell, 
must remain unsettled. It must be remembered, however, that nuclear 
migration between vegetative cells has been seen to occur in P. Poarum . 
It is also interesting to note that, just as in the aecidium, we find, in 
connexion with teleutospore-formation, a certain number of abnormal 
cells and spores which show three nuclei (Figs. 22 and 23). The similarity 
of abnormality may perhaps be taken as indicating a similarity in the 
methods by which the conjugate nuclear condition is brought about in the 
aecidium and young teleutospore sorus respectively. 
