FROMME: SEXUAL FUSIONS IN FLAX RUST 123 
“basal cell”’ is formed by the equal enlargement of the two fused 
cells, and the aecidiospore mother cell lies directly over the fused 
cells. The cases figured by Olive, on the other hand, show that 
the nucleus of one gamete passes into the other, and the gamete 
which is now binucleated elongates and functions directly as the 
“basal cell.’” Cases of this nature also occur in Melampsora Lini. 
It will be seen in the fusion shown in FIG. 15 that the gamete on 
the right has elongated and become the ‘‘basal cell’? and has 
cut off the first aecidiospore mother cell. The nucleus of the 
gamete on the left lies in the opening between the two fused cells. 
A comparison of this figure with F1G. 13 and 14, which are cases of 
equal contribution to the “basal cell,”’ will illustrate the difference 
between these two methods. It is interesting to find both of these 
methods occurring here in the same rust. 
Reference has already been made to a triple cell fusion, shown 
in FIG. 11, which lies in the center of a group of ordinary cell 
fusions. There can be no question that the condition there shown 
has been brought about by the fusion of three gametes instead 
of two. Fic. 16 shows an early stage of a triple cell fusion. The 
intervening cell walls are absorbed just as in the case of a double 
cell fusion, and a “basal cell’’ is produced which contains the 
nuclei and cytoplasm of three gametes. Fic. 17 is a case of a 
triple cell fusion where the three-legged base is especially distinct. 
These triple fusions are of tively frequent occu in my 
material. Fic. 18 (PLATE 9) shows a triple fusion which presents a 
still further complexity. It will be seen from the figure that two 
adjoining cells in the same filament on the right have fused with 
‘ single cell in another filament on the left. This has also resulted 
in * trinucleated ‘‘basal cell’’ but differs from the usual triple 
fusions in that two of the gametes come from the same filament. 
T have observed several other cases of this nature. It seems, then, 
that not only a single layer of gametes are produced, in this form, 
but occasionally another cell placed below the ordinary functional 
cells also has the capacity for effecting fertilization. The three 
nuclei thus associated in the same “‘basal cell” probably divide 
onjugately” to produce trinucleated aecidiospores. Fic. 19 
OWS a trinucleated aecidiospore mother cell which has just been 
formed by the division of the trinucleated ‘‘basal cell” on which 
