al 
1898-99. ] ON THE CYTOLOGY OF NON-NUCLEATED ORGANISMS, 483 
in the mitotic fashion, and Janssens claims to have observed the equa- 
torial plate and dyaster stages. In spore formation the nuclear mem- 
brane disappears, and the plane of the second division is at right angles 
to that of the first, the two spindles also being at right angles-to each 
other. Each spore is provided with a nucleus. 
Later Janssens, in conjunction with Leblanc, published a fuller and 
somewhat different account of the structure of the cell. They found in 
S. cerevisie and S. Ludwigzz a nucleus with a distinct nuclear mem- 
brane, caryoplasm, and a nucleolus constituted of nuclein. The caryo- 
plasm is formed of a fine network of fibrils intimately connected with 
each other and applied to the nucleolus. When, however, the cells are 
put in a fresh culture medium, the nucleus becomes vacuolized, but the 
nucleolus maintains its shape and central position, and the protoplasm 
remains homogeneous. The vacuolated condition ceases at about the 
thirteenth hour. In a longer stay in the medium the protoplasm 
becomes granular. Ordinarily the cytoplasm is formed of a typical 
reticular structure, the meshes of which contain granules. Both the 
contents of the meshes as well as the reticulum and its nodal points, in 
some cases, manifest a strong affinity for colouring matters, and it is evi- 
dent that this is due to a nucleo-albuminous substance dissolved in this 
structure. When the cells are grown on plaster blocks the granules 
may become very large and refracting, but when sporulation begins 
these granules disappear, presumably contributing a portion of the 
material which constitutes the spores. Glycogen in the cell ordinarily is 
dissolved in the enchylema, but when it is very abundant it localizes 
itself in vacuoles which may fill the cell. When the cell buds, the 
nucleolus elongates and divides, but the two parts remain united by a 
strand of substance apparently like fibrils, which may slightly resemble 
a spindle. The two nucleoli pass toward that part of the cell which is 
giving rise to the bud. The nuclear membrane and the caryoplasm 
disappear, leaving the nucleoli nude. A structure which resembles, to a 
certain extent, a cell plate, makes its appearance in the cell between the 
two nucleoli. The process up to this point is a rudimentary form of 
kinesis. One of two nucleoli slips into the bud, and now, if not before, 
the nuclear membrane re-forms about both. The bud thus constituted 
is, in all respects, like the mother cell. 
In the formation of the spores, the authors find that early in the spore 
mother cell the nucleolus divides, as already described, but the nuclear 
membrane does not disappear. This is not accompanied by any divi- 
sion of the cell. After some hours, however, only one nucleus with a 
large nucleolus is observed. The authors believe that the two nucleoli 
