80 WEATHERWAX: GAMETOGENESIS IN ZEA MAYS 
In 1901 Guignard (10) reported having observed this process, 
but his otherwise excellent paper was not illustrated. While his 
results have been generally accepted by morphologists, and made 
the basis of extensive work by geneticists, the desirability of a 
verification is attested by the number of students who are known 
to have attempted at different times to repeat his work. If 
negative results were generally published, we should, no doubt, 
have a much more voluminous literature on this point. 
In one preparation the writer observed the two fusions taking 
place simultaneously (Fics. 17, 18), but in a majority of cases one 
preceded the other. Whether or not there is a definite order in 
which the fusions occur has not been determined, because it is 
almost impossible to determine by appearance alone whether a cell 
under observation is an egg or a zygote. It is true in all cases, 
however, that several free endosperm nuclei are formed before the 
first division of the fecundated egg. 
At the time of fecundation the egg nucleus is often seen to 
have moved to one side of the cell (Fic. 16), and the polar nuclei 
may also migrate within a limited range, often approaching the 
micropylar end of the embryo sac. Whether or not there is any 
significance to be attached to these migrations has not been de- 
termined. 
These fusions take place while the egg nucleus and the polar 
nuclei are in a resting condition (Fics. 17-19). The chromatin 
is gathered into numerous round, globular bodies, some of them 
almost as large as a sperm; and these granules are loosely connected 
by strands composed of finer granules of similar appearance. 
That these chromatin bodies are not the “prochromosomes”’ of 
some authorities is attested by their number, which is far too great. 
XENIA 
As long as maize has been cultivated, it has been noted that, 
when white and colored varieties of some kinds were grown close 
together, the ears of the former were likely to bear a few colored 
seeds. The American Indians are said to have observed this and 
to have attributed it to the intermingling of the roots underground. 
Later, civilized man attributed the phenomenon to some effect of 
cross pollination, but its mechanism long remained a mystery. 
