350 BOTANICAL GAZETTE [May 
Material of the two-spored Agaricus campestris was prepared for 
study in the same way, but on account of the smaller size of the nuclei 
and the dense contents of the basidium, this plant does not offer favorable 
material. ; 
Fic. 1. Young basidium which is densely filled with cytoplasm and contains two 
primary nuclei—Fic. 2. The membranes of the two nuclei are in contact.—FIc. 3. 
Two primary nuclei in the process of fusion, but the nucleoli indistinct—Fic. 4. Fusion 
of the nuclei almost complete——Fic. 5. Basidium somewhat increased in size after 
fusion of primary nuclei.—Fics. 6 and 7. Older basidia in which the secondary nucleus 
occupies a position near the end of the basidium; structure of nucleus at this stage. 
very distinct.—Fic. 8. Division of secondary nucleus.—Fic. 9. Chromosomes moving 
to the poles of the spindle——Fic. 10. Chromosomes os iE of the spindle.—Fics. 11 
and 12. Daughter nuclei occupying different positions in basidium; usually near the 
end.—Fic. 13. Basidium showing four nuclei—Fic. 14. The four nuclei crowded 
together at some distance from the end of the basidium and the sterigmata begin- 
ning to form.—Fic. 15. The cytoplasm beginning to pass through the sterigmata to 
form the spores.—Fic. 16. A basidium in which the spores are almost mature; two 
nuclei still seen near the center of the basidium.—Fic. 17. Old basidium from which 
spores have fallen; two nuclei near the center. 
