274 
METHODS IN PLANT HISTOLOGY 
movement of the cilia should be distinguishable. Zamia is the only 
genus available in the United States; but even its rather small female 
cones, as they near the fertilization stage, will keep 4 or 5 weeks 
after they have been removed from the plant. 
Fig. 95 .—Ceratozamia mexicana: photomicrograph of a longitudinal section of a sperm, 
showing the very large nucleus, thin sheath of protoplasm which is thicker at the apical end, and 
blepharoplast cut across in various places and bearing numerous cilia. At this stage, the sperm is 
swimming in the pollen tube. Cramer, contrast plate. Negative by Miss Ethel Thomas. X506. 
In the region of Miami, Florida, pollination takes place late in 
December or early in January; blepharoplasts appear in March, and 
swimming sperms are found during the first 2 weeks of June. In 
