CYTOLOGICAL STUDIES ON CERATIOMYXA. 
EDGAR W. OLIVE. 
(With Plate XLVII.) 
Ceratiomyxa lias long remained the sole representative of 
the Exosporeae among the Myxomycetes. The following in¬ 
vestigation seeks to add certain cytological details to the ad¬ 
mirably clear and fairly complete description of the develop¬ 
ment of the fructification of this organism by Famintzin and 
Woronin in 1873. The present preliminary study has led to 
the interesting discovery that the nuclear divisions which re¬ 
sult in the formation of the four-nucleated spores are appar¬ 
ently reduction divisions. Consequently, while convinced that 
a sexual fusion occurs somewhere in the life cycle of Ceratio¬ 
myxa, I have not yet been able, however, to solve the problem 
as to where such a fusion occurs. 1 
As pointed out by Famintzin and Woronin, Ceratiomyxa 
was first described and figured by Micheli in 1729 1 , and later 
by many other observers. Its life history and affinities were 
not understood, however, until the investigation of the Russian 
i Since this article went to press, the fusion of the nuclei in pairs 
was found to take place toward the close of the cleavage stage; this 
was followed almost immediately by synapsis. A paper on the subject 
was read at the December meeting of the A. A. A. S., which was sum¬ 
marized later in Science (Olive, ’07). The view was therein expressed 
that the conditions in Ceratiomyxa are somewhat similar to those in 
the rusts, in that the three morphological stages of the sexual cycle 
are similarly spaced; i. e., the cell fusions in both organisms are far 
removed from the final nuclear and chromatin fusions. A little later, 
Jahn (’07) published an account of nuclear fusions and division in 
Ceratiomyxa, which differs widely from that described by the writer. 
Jahn finds nuclear fusions as well as reduction divisions occurring at 
a much earlier stage than I. The two later divisions in the young spore 
he apparently regards merely as vegetative divisions. The shrunken, 
synapsis-like condition described ip, the present paper Jahn apparently 
has not seen. 
