1056 
Vol. XXVIII, No. 10 
Journal of Agricultural Research 
obviating the necessity for a reduction nuclear division. For this reason the 
number of cells in a rust protobasidium need not always be four. The presence 
of some male element exercising its secondary function indicates maturity and 
cell fusions will occur, while inhibition of such a development is manifested by 
the omission of cell fusions. 
Aside from the immediate developments dependent directly on fecundation, 
there is frequently a whole series of activities well known and recognizable in 
sexual reproduction in plants and animals which result from the expression of 
sexuality in a secondary capacit%\ One can conceive of such a thing as the agent 
inaugurating cell fusions in the short-cycled orange-rust being ordinarily “ linked ” 
with or dependent on the factor which stands for spermogonial development, 
yet occasionally becoming separated from this factor. Ordinarily then the ap¬ 
pearance of spermogonia would be followed by cell fusions, except where there 
has been a transfer of the factors for fusions to some other determinant where 
it could no longer express itself normally. 
The Gymnoconia as noted becomes short-cycled by omitting or suppressing 
the telial stage. If that combination of factors which was instrumental in 
bringing about a shortening of the life cycle were unconnected with maleness 
in any way, the rust would develop its spermogonia, cell and nuclear fusions 
would follow as before, and the spores would germinate with 4-celled promycelia. 
If one should be able to prove that in the short-cycled form there are no nuclear 
fusions and that chains of binucleated or multinucleated spores may arise without 
cell fusions, it would be further evidence of the complexity of the factors involved 
in the development of the various spore forms. 
The writer has pointed out that the spores with one nucleus are smaller than 
than those with two or more. This agrees with what Kursanov ( 8) says of the 
uninucleated spores of Aecidium leucospermum. Kunkel (5) figures uninucleate 
aecidiospores of the short-cycled orange-rust, but he interprets them as resulting 
from nuclear fusions. It should be noted that in his figures the uninucleated 
spores are in both cases much smaller than the binucleated spores. 
The very fact that promycelia with irregular or odd numbers of cells—three 
to nine are found—and that as many as five nuclei may occur in one cell, would 
indicate that this multicellular, multinuclear condition has not arisen as a result 
of fusions of nuclei in pairs in the aecidiospore followed by regular reduction 
divisions. 
It is inconceivable that a 7-nucleated aecidiospore which was found in an 
aecidium, the other spores of which were mostly uninucleated, could have been 
the result of the fusion of seven cells. When such a spore germinates, a pro¬ 
mycelium is formed which, from the nature of its origin, will be normal; but from 
a viewport fixed by previous misconceptions, will be abnormal. The writer has 
found that in certain strains of the short-cycled orange-rust practically every 
promycelium is 4-celled. This can almost be determined in advance by the 
form and size of the aecidiospores. In any culture where the spores vary con¬ 
siderably in shape and size some “abnormal” promycelia will be developed. 
There is a rather fascinating hypothesis which might be brought forward to 
account for the frequency with which one finds the omission of the spermogonial 
stage is associated with the omission of cell fusions and with the production of 
1-nucleated spores in the aecidium. 
If as Kniep maintains in the anther smut, Ustilago anther arum, the two sporidia 
at one end of the promycelium are “plus” and the other two “minus,” then the 
host can be infected so that the rust develops normally only when a sporidium of 
each sort takes part in the infection. Infection from a single sporidium might 
be possible only in case the strain happened to be capable of, say, an androgenetic 
development assuming that + and — refer to femaleness and maleness. In this 
