3 193.) On the Development of the Caryopsis. 217 
serve in some degree to give direction to the pollen tube. 
Hackel"* says that the outer integument of the ovule of the 
ram nee ‘thas very delicate walls, and forms a conductive 
tissue for the pollen tube upon the anterior side.” Figs. 3, 4. 
The nucellus consists of large isodiametric cells with small 
wuclei and scant contents. It is bounded by an epidermis 
with strongly cutinized outer walls. This cuticle is conspic- 
uous in all stages of growth by reason of its great affinity for 
staining fluids. Toward the base of the nucellus, in its an- 
terior part is found the embryo sac. In this grain it is very 
large, being readily sectioned even by free-hand methods. 
For avery short time after fertilization no general change is 
noticeable in the ovule outside of the embryo sac. As the 
first Point of 
rr com 
- Previous to the colla 
‘tegument S$ 
ency to 
bee ~ of the outer integument, the inner 
weake ittle change. | Shortly, however, a slight 
fone ats seen, especially in the external layer of 
any the Partitions become wrinkled. That a 
ie “inner integument with the ovary wall in 
cake integument has disappeared. The 
© undergo increased compacting to make 
| m. 
S¢, profound changes in the pericarp 
ifest themselves, Toward the top of the ovule, 
Walled parenchyma of the middle and 
aa. 1S Cons a compacting, of the cell walls 
hich this “ge The outer boundary of the region in 
es place, is rather regular and is very 
