762 Wisconsin Academy of Sciences, Arts, and Letters. 
of the nuclei does not take place before spore formation, as has 
been described for other Myxomycetes, but rather after the 
event. I have never been able, in fact, to find any sign of nu¬ 
clear division in the active fructifying plasmodium of this 
form previous to cleavage. After the short period of rest fol¬ 
lowing cleavage, the large nucleus of each protospore proceeds 
to divide twice in rapid succession (Figs. 11-14). These 
divisions are not, according to my interpretation, of the nature 
of an intrasporal germination, but they are similar rather to 
the double division seen in spore mother-cells. These two suc¬ 
cessive divisions, occurring as they do in this place, immediate¬ 
ly following the condition so closely resembling synapsis, fur¬ 
nish, to my mind, convincing evidence that we have here to do 
with a reduction division, following a true synapsis. The im¬ 
portant bearing of these facts I hope to take up later; we may, 
however^ simply observe in passing that, in my opinion, these 
phenomena clearly establish a nuclear fusion somewhere in 
the preceding life history of Ceratiomyxa. It should be here 
noted, in fact, that Prowazek ( ? 04) has recently figured sec¬ 
tions of the plasmodium of Physarum psittacium, in which 
he shows the nuclei fusing in pairs, but he does not explain 
whether this takes place in the vegetative or in the fructifying 
plasmodium. 
After cleavage is completed, each uninucleated cell continues 
its creeping movement, acting now as an independent Amoeba. 
The cells lie at first closely pressed together^ presenting from 
the surface view a honeycomb-like appearance. The creeping 
movement from now on is outward and at right angles from 
the moist, slimy surface of the sporophore on which the cells 
rest. Arching outward, each Amoeba- like cell soon forms a 
spherical, swollen end, borne on a slender stalk. All of the 
protoplasm appears finally to move out into the rounded end, 
leaving the stalk as a long, gelatinous filament, attached to the 
slimy substratum (Fig. 13). Somewhere near the close of 
the growth of the stalk, the single nucleus divides twice, as 
has been described above, so that the mature resting spore con¬ 
tains four nuclei (Fig. 15). 
The mature fructification of Ceratiomyxa hydnoides is thus 
