768 Wisconsin Academy of Sciences, Arts, and Letters. 
be asked, Is the gradual attenuation of the strands in the pro¬ 
toplasmic meshwork of the forming sporophore of the nature 
of a cleavage ? It is true that the phenomenon is accompa¬ 
nied throughout by a gradual increase of exposed surface, 
therein resembling the process of cleavage. But the plasmo- 
dial reticulum throughout the whole creeping movement re¬ 
mains a connected whole; there is no cutting apart or pulling 
apart of portions of the protoplasm until cleavage proper sets 
in. The gradual attenuation of the strands is not, therefore, a 
true cleavage, but the process accomplishes, partially, the same 
end as cleavage. The final cleavage in Ceratiomyxa is con¬ 
sequently much abbreviated as compared with the phenomenon 
in Fuligo and other sporangia. The cleavage stage in Fuligo 
may in fact be said to correspond to cleavage plus the inter¬ 
polated active period of attenuation in Ceratiomyxa. 
During the period in Fuligo when the cake-like, sessile mass 
is undergoing cleavage, the protoplasm, as evidenced by 
general appearances, seems to be more or less quiescent. The 
phenomenon in general appears to take place, in fact, during 
a more or less quiescent stage. But almost incessant creep¬ 
ing movements, on the other hand, seem to characterize the 
fructifying protoplasm of Ceratiomyxa. The plasmodium 
piles up on the substratum and begins to form at certain points 
papillae. As these papillae grow out to form the cylindrical 
sporophores, the protoplasmic meshwork in each apparently 
undergoes incessant upward movement, creeping finally to 
the surface of the gelatinous structure. Cleavage now takes 
place, and even in this condition, at least in such late stages of 
the process as are shown in Figure 5, the creeping movements 
have not appeared to cease entirely, for the cells seem to pull 
apart after the manner of a dividing Amoeba. 
It is well known, however, that the Amoeba and other uni¬ 
cellular organisms, when ready to divide, withdraw their pseu¬ 
dopodia, and, at least at the beginning of the process, cease their 
active movements ; and this is probably the case also in Cera¬ 
tiomyxa. Undoubtedly such masses as are shown in Figure 
4 remain more or less quiescent during cleavage, as evidenced 
by the appearance of the narrow furrows which cut into the 
