The accumulation of this lignin is known to be second- 
ary, in that it occurs after the glumes have already at- 
tained optimum length and during the development of 
the caryopsis. If fertilization does not occur, then the 
glumes remain non-lignified and finally become papery. 
If only a portion of the ear is fertilized, then only those 
glumes which are either directly associated with fertilized 
ovaries or indirectly associated by being adjacent to spike- 
lets with fertilized ovaries will become lignified. This im- 
mediate effect of fertilization in stimulating lignification 
of maternal tissue occurs also in teosinte and T’ripsacum. 
Also the cupule of maize, as well as its counterpart in 
these close relatives, is included in the same metaxenial 
phenomenon. 
Certain features of the vestigial glume syndrome seem 
to be correlated with morphological homologies. The 
effect of the Vg gene in reducing glume size appears to 
be accomplished largely by suppression of the lateral 
wings (probably sheath-auricles), with the remaining por- 
tion representing a small, highly lignified sheath (com- 
pare figs. 8 and 4in Plate IX). In addition to the lateral 
wings of the glumes, the /’2 gene also causes, under cer- 
tain conditions, a reduction of the lateral wings of the 
cupules and the ligules of the leaves; this last-named 
effect was noted first by Laughnan (1956). Glume wings 
and ligules have at least two features in common in that 
both of them are papyraceous in texture and are situated 
as erect prolongations of the sheath, or its homologue, 
adjacent to the actual or theoretical insertion-point of 
the blade. Furthermore, these structures appear to be 
homologous, as is suggested by the vegetative leaves of 
certain grasses (4 mmophila arundinacea) with blades that 
are narrower than their sheaths. In such grasses, the 
lateral portions of the ‘‘ligule’’ elongate and develop as 
sheath-auricles with the same textural characters as the 
| G9 | 
