Olive—Oytological Studies on Ceratiomyxa. 771 
dylium, a still more complicated method of raising the spores 
above the substratum has been evolved. Certain cells in the 
center of the mass become vacuolated and otherwise modified 
to form a supporting column. As the colony ascends this stalk, 
the latter grows in height by the addition of more modified 
cells on the top of the column. The ascending colony leaves 
behind a mucous substance which thus forms a thin, slimy 
sheath, which encloses and greatly strengthens the parenchym¬ 
atous stalk, as well as provides a cementing substance to bind 
the expanded base of the stalk fast to the substratum. 
SUMMARY OF CONCLUSIONS. 
The principal points brought out in the foregoing paper 
may be summarized as follows: 
1. Sexual reproduction is without doubt present in Ceratw- 
myxa , since there occurs in connection with spore formation 
what appears to be a reduction division of the nuclei. A stage 
resembling synapsis, in w T hich the chromatin lies in a shrunken 
mass at one side of the large nuclear cavity, is followed after 
a short period by two rapidly recurring nuclear divisions. The 
young spores, or more properly speaking, the spore mother-cells, 
contain thus at first but one large nucleus; while the mature rest¬ 
ing spores, as a result of the subsequent double division, come 
to contain four smaller nuclei. This indication of a reduction 
division at the time of spore formation is made the basis of 
the conclusion that, in addition to the multiple cell-fusions to 
form the plasmodium, there must occur necessarily a union, 
probably in pairs, of the nuclei, somewhere in the previous 
life-history of the organism. 
2. The cleavage of the plasmodium of Ceratiomyxa to form 
spores is a progressive process, and not simultaneous, as 
maintained by Famintzin and Woronin, since the attenuated 
reticulum, which spreads in a thin, delicate network over the 
surface of the cylindrical sporophore, is first cut up into mul- 
tinucleated segments which later are still further cut up into 
uninucleated cells. By the time cleavage sets in, the strands of 
the reticulum generally appear to have become greatly atten¬ 
uated, so as to show frequently only one nucleus in optical cross 
