36 Wisconsin Academy of Sciences, Arts, and Letters. 
these figures were derived were respectively 59, 68, 60; 62, 6If, 
63; 60, 55, 59; and 60, 61, 58. The average for all of these 
countings is 60, which it seems probable is slightly below the 
number of chromosomes characteristic of the prothallium in 
this species. The higher numbers were obtained in spindles 
where the chromosomes were spread out to the best advantage 
for counting. It is probable that sixty-two or sixty-three is 
more nearly correct than the average of the six numbers. 
The chromosome number in the dividing nucleus of the young 
sporophyte was determined in the same way. In sections 
through the young apogamous outgrowth, division figures are 
comparatively abundant. An equatorial plate stage is shown 
in figure sixty-one. It was taken from a point near the newly 
formed stem apex. Here, too, as in the division figures in the 
gametophyte, the spindle is broad-poled. The denser part of 
the cytoplasm is massed about the poles of the spindle. To¬ 
ward the periphery of the cell there is a much greater propor¬ 
tion of cell sap. The slender chromosomes, a few of which 
show the longitudinal split, are apparently attached by one end 
at the equator of the spindle. The free ends may extend to¬ 
ward the poles or radially outward. They hide from view the 
greater part of the spindle fibres. About a third of the total 
number of chromosomes are represented in the figure. 
The counting of the chromosomes was done as before, each 
number given representing the average of three counts for the 
same nucleus. The division figures from which counts were 
made were from different parts of the young sporophyte. The 
majority were in the central mass of tissue near the base of 
the stem apex; some came from the apical region of the young 
leaf. The numbers obtained in the individual countings were 
63, 61/-, —ave. 63; —— ■, — ave. 61+; 63, 69, —average 66; 
59, 59, 63, —average 60; 56, 58, 59, average, 58; 58, 61, 58 ,— 
ave. 59; 58, 60, 59, —average 59; 62, 66, 6J+, —ave. 61+; and 61, 
65, 62, —average 68. The average of the means so obtained is 
62. 
The greater variation in the numbers here is probably due to 
inaccuracies in counting and does not prove irregularity in the 
chromatin content of the nuclei. 
