June 7,1924 Ummicleated Aecidiospores in Caeoma Nile ns 1053 
again contains two. This first division may be delayed and later occur in the 
germ tube. The first septum is laid down before the second division occurs. 
Finally, a single uninucleated sporidium develops from each of the four cells. 
Such a course of procedure, following as it does what is known of nuclear behavior 
during the formation and germination of the teleutospore of the rusts, has been 
considered by some authorities to be sufficient evidence to warrant calling the 
aecidiospore of an Endophyllum a teleutospore. Evidence is accumulating very 
rapidly, however, to indicate that while the spore forms of the rusts as morpho¬ 
logical entities are fixed because of their phylogenetic antecedents, the methods 
by which a particular spore form arises and the nuclear behavior at its origin and 
during germination are far from generalized, orderly, or fixed processes. 
In the Florideae the methods of origin of the cj^stocarps and nuclear behavior 
in the cell activities involved in the formation of carpospores vary in some 
essential details with almost every genus in the five orders. One certainly must 
expect that their rust offspring will be just as individualistic. 
There is an Endophyllum, E. euphorbiae-silvaticae, in which, as proved by 
Sappin-Trouffy (14) and Moreau (12), the two nuclei originally^ entering the 
aecidiospore never fuse. They pass out into the young promycelium and divide 
once, giving the four nuclei for the maturing of four sporidia. According to 
Maire (10), one of the two original nuclei of the spore of E . valerianae-tuberosae 
degenerates so that a reduction division could not follow. 4 Moreau (11, 12) 
has furthermore given convincing proof that there is a form of E. euphorbias 
with uninucleated aecidiospores and that there are no cell fusions in its aecidium. 
Her figures of the germinating spores and of the promycelia are, however, not 
all that could be desired. Whether or not Moreau believes that the promycelia 
from these uninucleated spores would “normally’’ be 4-celled and produce four 
spores is not clear from her papers. Nothing in her figures suggests such a 
thing. 
Certainly one finds no explanation of the peculiarities of the orange-rust in 
Puccinia malvacearum, the only rust lacking spermogonia that has been thoroughly 
studied as to its cytology and physiology. It is a perfectly *' 4 normal'*’ short- 
cycled form, except for its lack of spermogonia. In the absence of any definite 
knowledge respecting spore formation and the nuclear phenomena in those other 
rusts which lack spermogonia it would be futile to speculate on the meaning 
of the loss of these structures in the strain of Caeoma nitens under discussion. 
Knowing nothing as to the development of spermogonia by the uninn cleatum” 
strain of Endophyllum, and nothing regarding the number of nuclei and cells 
in the promycelium except that the germ tubes that were obtained did have 
septa, it can only be said that further research may show that this Endophyllum 
may resemble the orange-rust not only as to the origin of its uninucleated spores, 
but also in the suppression of its spermogonia as well as in the formation of 
2-celled promycelia. Germination of the spores of the form of E. euphorbiae , 
which Maire (10) claims becomes uninucleated by degeneration, should also 
be studied. 
Two other European cytologists are accumulating evidence proving that 
life histories of species of rusts are not always as fixed events as has heretofore 
been generally believed. Kursanov (7) has pointed out that in certain sori of 
Aecidium punctatum the peridial cells and their interstitial cells are uninucleated. 
The spores in such a sorus are uninucleated except that here and there a spore 
has two nuclei clearly as the result of nuclear division. Nothing is said of the 
manner of germination of the uninucleated spores. There is a form of Aecidium 
4 In a later paper (Maire, R. Devolution nucl£airf chez les endophyllum. Jour. Bot. [Paris] 
14:80-97, 369-382, pi. 3. 1900) he figures 2-celled promycelia, failing to furnish any evidence by figures, 
that the aecidiospore becomes uninucleated by degeneration. 
