FROMME: SEXUAL FUSIONS IN FLAX RUST 129 
This feature may furnish a further basis for use in the classi- 
fication of the Uredineae. 
The fusing cells in the aecidium are entirely similar and form 
a fairly even series at the base of the sorus. Two short sterile 
cells are normally formed above each gamete. Their function 
is evidently protective and they may correspond to the pseudo- 
parenchyma of young aecidium cups. Sexual fusions are very 
abundant in this form, and many pairs of gametes in various 
stages of union can be found side by side in the same preparation. 
Fusions of three and four cells have also been found in addition 
to the normal two-cell fusions and are perhaps to be regarded as 
further evidence that the sexual processes as found in the rusts 
are of a secondary character. Large multinucleated cells are also 
present in the same sorus with two-, three-, and four-cell fusions. 
COLUMBIA UNIVERSITY. 
LITERATURE CITED 
Blackman, V. H. On the fertilization, alternation of generations and 
general cytology of the Uredineae. Ann. Bot. 18: 323. 1904. 
Blackman, V. H., & Fraser, H.C.I. Further studies on the sexuality 
of the ieadiacan: Ann. Bot. 20: 35. 1906. 
Christman, A. H. Sexual reproduction in the rusts. Bot. Gaz. 39: 
267. 1905. 
—— The nature and development of the primary uredospore. Trans. 
Wisconsin Acad. Sci. 15: 517. 1907. 
Kurssanow, L. Zur Sexualitit der Rostpilze. Zeits. Bot. 2:81. 1910. 
Maire, R. La biologie des Urédinales. Prog. R. Bot. 4: 109. 1911. 
Olive, E. W. Sexual cell fusions and vegetative nuclear divisions in 
the rusts. Ann. Bot. 22: 331. 1908. 
—— The relation of “conjugation”? and “ nuclear migration” in 
the rusts. The relationships of the aecidium-cup type of rust. 
Science II. 27: 213. 1908. 
Origin of heteroecism in the rusts. Phytopathology 1: 139. 
I9II. 
Taubenhaus, J. J. Acontribution to our knowledge of the morphology 
and life history of Puccinia Malvacearum. Phytopathology 1: 
55: 1911. 
