24 CONIFERJE. 
which indeed they may be confounded. They are however 
at once known by the presence of granules in their heads, the 
celis being entirely destitute of these bodies. I may observe, 
that the boyaux appear to be confined to the truncated dilated 
bottom of the excavation. Their course cannot be traced 
unless by dissection; the tissue being exceedingly soft and 
rendered opaque by the pressure of even the thinest mica. 
They are filled with granules, which are as usual of two sizes 
large and small, both being endowed with mobility but not in 
a high degree. 
'The tissue of the TS also surrounding the excavation, 
is now of a high brown colour. 
I had set out with the supposition, deduced from observa- 
tions on Nelumbium and Crotalaria, that there would be mere 
application of the pollen to the nucleus, and that no pro- 
duction of boyaux would take place. And I argued that the 
. boyaux were produced in other plants in order to bring the 
surface of the pollen into contact with the nucleus, taking 
this view of the case, the granules would perform some other 
function, the mere nutrition of the containing membrane. 
It is now evident that mere contact of the pollen or of itgg 
tubes with the nucleus is not sufficient, as might indeed have 
been surmised from what takes place in Asclepiadee. But 
that actual penetration of the boyaux into the substance of 
the nucleus is absolutey essential. The determination of the 
precise state of the pollinia at the period of the first appear- 
ance of the embryo, will throw great light upon this most 
intricate subject. If this does appear while the boyaux are 
appreciable, the tardiness of the appearance of the embryo 
inthe Mergue Cycas, will depend upon impregnation not 
having taken place. 
Ten days after. The excavation appears to be lined towards 
its base with a grumous mucilaginous fluid in which the pollen 
granules are immersed, at least this is the appearance that à 
longitudinal section presents. The boyaux have no apparent 
determinate direction, but penetrate the tissue at the base and 
M EU. 
TOSS TAMEN 
TAN EEA Hag d eee 
