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Tg909] COULTER—EVOLUTION AMONG GYMNOSPERMS 97 
_ In Zamia, for example, which illustrates the extreme amount of 
reduction among cycads, the proembryo is a relatively small amount 
of tissue at the base of the egg. Among the Coniferales this reduc- 
tion has been carried forward to a much greater extent, 16 free nuclei 
appearing sometimes, 8 free nuclei being the prevailing number, and 
4 free nuclei being occasionally attained. This results in a pro- 
embryo consisting of a small and definite number of cells, with dis- 
tinctly distributed functions. Now and then among gymnosperms ° 
(as in Sequoia), there is no free nuclear division, but these are inter- 
esting rather than significant exceptions. Even among the Gnetales 
itis found that a certain amount of free nuclear division precedes 
wall-formation. That this reduction of the free nuclei before wall- 
formation is significant, is shown by the fact that among angiosperms 
free nuclei have disappeared, and wall-formation accompanies the 
first division of the egg-nucleus. 
THE UNIVERsITY oF CHICAGO 
