Olive—Cytological Studies on Ceratiomyxa . 763 
seen to possess a very peculiar structure. All of tile protoplasm 
has now migrated to the ends of numberless long, slender stalks 
where it normally passes through a resting period as minute 
oval four-nucleated spores. Nothing but slime remains in the 
conspicuous supporting structures of the sporophore—the base, 
the main axis and the slender stalks. It is true that other 
organisms—other members of the Mycetozoa, the Labyrinthu- 
leae, and the Myxobacteriaceae—employ slime as an impor¬ 
tant element in building up their fruit bodies, but none, so far 
as known, use such an inert substance in their fructifications 
so extensively or so successfully as does Ceratiomyxa. 
GENERAL DISCUSSION. 
It has been noted above that the process of cleavage in the 
plasmodium of Ceratiomyxa differs in an important respect 
from the cleavage described for other forms. Harper (’00) 
has pointed out that, while the division of the nuclei in Trichia 
and other genera is already completed before spore forma¬ 
tion begins, in Fuligo , on the other hand, nuclear division 
proceeds simultaneously with the process of cleavage. Cerar 
tiomyxa , as we have already noticed, presents still a third 
condition, in that cleavage is completed before nuclear divi¬ 
sion begins. From this fact result the four-nucleated spores 
of Ceratiomyxa ; whereas in all other Myxomycetes, as far as is 
known, the spores are uninucleated. Cell division in Cera 
tiomyxa thus precedes nuclear division. Lister (’03) came to 
the conclusion that, “leaving aside the question of the sclero- 
tium, whenever cell division occurs in the life history of the 
Mycetozoa the nuclei divide by karyokinesis” (p. 54-1). Since 
Ceratiomyxa reverses the usual order for Myxomycetes, by 
having cell division precede , instead of follow, nuclear division, 
it is evident that Lister’s statement will not hold. Harper 
(’99, ’00), Timberlake (’02), and recently Swingle (’03) have 
shown also for certain sporangia that nuclear division neither 
determines nor is in any way connected with cell division, and 
the writer has recently extended this discovery to certain fil 
amentous fungi (’06). The considerable number of cases now 
47—S. & A. 
