190] CELL AND NUCLEAR DIVISION IN FULIGO VARIANS 229 
oriented without especial reference to the distribution of the 
nuclei, thus cutting off larger and smaller segments with more 
or fewer nuclei, they are now to proceed midway between each 
pair of nuclei, so that equal and uninucleated masses will result. 
As already noted, the impression is very strongly given by these 
dense rounded masses separated by relatively watery regions 
that a contraction has taken place about each nucleus as a cen- 
ter. Such conditions might be produced by a contraction origi- 
nating in the structure of the cytoplasm itself, or in a pull 
exerted upon the cytoplasm by the nucleus. After the forma- 
tion of these hyaline areas, the cleavage is completed by the 
furrowing of the plasma membrane along the lines marked out. 
A later Stage than that shown in fig. 6, in which certain furrows 
have already cut deeply down into the hyaline regions, is shown 
in fig. 7. The furrows are apparently formed just as they were 
in the earlier stages, but they follow the hyaline areas, and thus 
the separation of the uninucleated masses is completed. Such 
Cleavage as this is progressive in the sense that both the hyaline 
“sions and the constriction furrows are developed gradually 
from the surface inward. When complete, however, it results 
in the simultaneous production of a number of uninucleated cells 
“qual to the number of nuclei in the original mass. And in this 
Sheet it differs markedly from the cleavage in the earlier 
wa 2 which larger multinucleated masses are progressively 
ae. oy Sapa with fewer and fewer nuclei. I have 
“ag a similar differentiation of a hyaline region pre- 
of ani. the plane of cleavage in the formation of the aporne 
own in a (4) 2. 25, jig. 21). In this figure resting nucle are 
throuch ° groups, between which a less dense zone is formed, 
8) which later, as is Shown in jig. 22, a cleavage furrow 
he appearance was little regarded in my description 
oe ae 
of Clea ‘ i nee 
Stage Ohm a Pilobolus, but its appearance at a similar late . 
‘Siderable <; ©avage of Fuligo indicates that it may have con- 
Ruclej © Significance in connection with the relations of the 
at least % Cleavage Phenomena. The hyaline areas, in Fuligo 
@ppear at about the stage in cleavage when the furrows 
