FROMME: ZEXUAL FUSIONS IN FLAX RUST 115 
The subsequent budding off of the primary uredospores in a 
fashion similar to that described by Christman confirms his 
evidence that the primary uredospores and aecidiospores are 
morphologically equivalent. Although Christman did not find 
the fusion stages in Caeoma nitens, his material being rather old, 
Olive figures two cases (fig. 35 and 36) for this form, where the 
fusion occurs between cells placed adjacent and parallel, similar to 
Christman’s figures of Phragmidium speciosum but without show- 
ing sterile cells. He also figures a third case where the nucleus of 
one cell is passing into a cell placed immediately above it but be- 
longing to a distinct hypha. This ashe points out is very similar in 
appearance to Blackman’s (’04) fig. 66 and 68. Fig. 34 and 36 were 
drawn from the same section and were but a short distance apart. 
This instance, in conjunction with his observations on Triphrag- 
mium, convince him that Blackman’s “nuclear migrations’’ and 
Christman’s “fusion of equal gametes”’ may occur in the same rust 
and in the same pustule. Sexual fusions may begin through a pore 
which is narrow at first so that the nucleus is constricted in 
Passing. Later this pore may broaden and the entire contents of 
the two cells fuse. He would distinguish between such cases 
and cases of undoubted pathological migrations such as he finds 
between the multinucleated cells of the aecidium of Puccinia 
Cirsit-lanceolati. In the typical microform, Puccinia transformans 
on Tecoma stans, fusion is shown in the teleutosorus between the 
end cells of two hyphae in one instance, while in another the end 
cell of one is fusing with the penultimate cell of the other. The 
fusions here are immediately followed by growth which results in 
teleutospores borne on several binucleated cells. The sporophyte 
8eneration in this case consists, then, of only a few, three or four, 
cells. In Uromyces Scirpi and Puccinia Cirsui-lanceolati, as well 
as in some eight other species, he found one or more large multi- 
nucleated cells at the base of the young aecidium cups. He is 
inclined to interpret these as sporophytic cells in which nuclear 
division has Proceeded faster than cell division, due possibly to 
the stimulus to growth derived from the sexual act. He suggests 
© possibility that the solution of the problem as to the develop- 
ment of the aecidium cup with its peridium and apparent central- 
zed structure may be found in these multinucleated cells. Es- 
