522 
PHANEROGAMS. 
neck is separated from the rest by division, and a small cell is thus formed shortly 
before fertilisation {i. e. before the access of the pollen-tube to the endosperm) ; 
this cell being clearly equivalent to the canal-cell so often -mentioned in Vascular 
Cryptogams which is afterwards converted into mucilage ^ In Abies canadensis and 
excelsa and Pinus Larix this canal-cell is, according to Strasburger, very evident ; 
while in the Cupressinese {Thuja, Juniperus, and Callilris) its demarcation from the 
rest of the contents of the central cell is only slight. As in those Vascular Crypto- 
FIG. -^^^.—Taxits canadensis (after Hofmeister). A longitudinal section through the upper end of the endosperm ^ (ä 
and the lower end of the polieu-tube p, c c the archegonia, d their stigmatic cells, the left archegonium is fertilised, x rudi- 
ment of the embryo (June s), (X 300). B part of the endosperm with an archegonium, the embryo of which v is already 
further developed, / the pollen-tube ([une 10) (X 200) ; C longitudinal section of a nucellus (June 15), nucellus, ee endo- 
sperm, / pollen-tube, v v embryos proceeding from two archegonia (X 50). 
gams where the ventral part of the archegonium is plunged in the tissue of the 
prothallium, the neighbouring cells become transformed by further divisions into a 
parietal layer surrounding the oosphere, so the same thing takes place also in the 
endosperm of Coniferse. In the Abietinese each archegonium is separated from an 
adjacent one by at least one, often by a large number of layers of cells : those of the 
Cupressineae, on the other hand (Fig. 355, cp), are in lateral contact. The arche- 
^ In Figs. 354 and 355, which are transferred from the first edition, the canal-cell is not 
indicated. 
