KiIRKWoOOD: POLLEN-FORMATION IN CUCURBITACEAE 227 
the development of the mother-cells they are quite conspicuous 
even under a relatively low magnification (75 diameters). They 
are a series of short, crooked, darkly-staining fibers, which lie | 
approximately parallel to one another on one side of the nucleus 
and about half way from the nucleus to the wall. They make 
their first appearance when the mother-cells are about half or two 
thirds grown and persist until the cytoplasm assumes the radial 
structure. As this change takes place they gradually disappear. 
About the time that the dark bodies disappear certain minute 
darkly-staining granules may be seen scattered promiscuously 
through the cytoplasm in its radial stage and during mitosis. 
_ The rod-like bodies are remarkably constant features in J/- 
crampelis, and appear when different staining reagents are used. 
It was first thought that they were portions of the nuclear chro- 
matin which had been struck out into the cytoplasm in the process 
of cutting, but when it is observed that in the same section where 
many pollen-mother-cells are visible these bodies lie on all sides 
of the nuclei, such a conclusion as to their origin must be aban- 
doned. Moreover in the same section some cells show them 
disposed horizontally, others show them in transverse section as 
a group of small black dots. It has been said that the fibers lie 
about parallel but occasionally they may assume a more or less 
radial arrangement around a certain point in the cytoplasm. They 
remain quite distinct up to the time when the cytoplasm begins to 
draw away from the cell-wall. The ends of these rods seem to 
weave in with the cytoplasmic meshes, especially toward the 
periphery of the cell where the reticulum is coarser. During the 
Progress of the tetrad divisions the spherical, darkly-staining 
masses may be seen scattered through the cytoplasm, but near 
the close of the division they become clustered about the nuclei, 
and thus are divided among the microspores. They increase in 
Size with the development of the spores and become very con- 
spicuous until the pollen-grains near maturity when they grad- 
ually disappear. Bodies of an apparently similar nature have 
been found by Strasburger*™ in the pollen-mother-cells of Larix, 
and Allen’, working upon the same subject, refers them to the 
class of extranuclear nucleoli and believes them to be proteid 
matters precipitated by fixing agents. But he finds them also in 
