1184 Wisconsin Academy of Sciences, Arts, and Letters . 
constructed and have increased considerably in size. The long 
beaks on the nuclei are very distinct. The centers at this stage 
are as near the plasma membrane as at a later stage when the 
rays are bent downward, some of them appearing to be very 
near. Figure 11 shows the fibres when they are just begin¬ 
ning to bend toward the nucleus. Here some of the centers are 
very near the wall and the rays have still to curve about the nu¬ 
cleus. The series of stages here makes it evident that in Geo- 
glossum the rays must bend downward through the cytoplasm 
and that they are not, as Fraser (16) has suggested, bent back¬ 
ward over the nucleus as the central body pushes its way out¬ 
ward through the cytoplasm at the end of the third division. 
Harper’s (25) hypothesis, that the movement of the astral 
rays in free cell formation can be compared to that of cilia, re¬ 
ceives strong support from the conditions found in Geoglossum. 
The rays here move through the cytoplasm in toward the nucleus 
when there is no indication of the movement of the central 
bodies outward. 
That the movement of the astral rays should resemble that of 
cilia is quite in harmony with the phenomena found in the de¬ 
velopment of cilia and flagella in other cases. In the for¬ 
mation of the antherozoids in the ferns and cycads the cilia are 
formed inside of the cell by growth outward from the blepharo- 
plast, and only later do they make their way through the plasma 
membrane to function as motile organs. 
As noted above we have a further striking example of the 
similarity between cilia and rays of the polar aster in the case 
of the spermatocytes of Pygaera bucephala as described by 
Meves (32). His figures suggest a very close resemblance be¬ 
tween the astral rays and the cilia or flagella. According to 
Meves both the cilia and astral rays grow out from the 
centers. The ray, which runs out to the very tip of the pseu¬ 
dopod can be imagined to grow longer and longer while the 
pseudopod becomes thinner and thinner until only the ray can 
be made out when we have a cilium. At the close of the second 
division but one pseudopod remains and that one contains the 
axile thread of the sperm. The appearance here is strikingly 
