522 



PHANEROGAMS. 



neck is separated from the rest by division, and a small cell is thus formed shortly 

 before fertilisation {t. 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 Cupressineae {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. 354. — Taxiis canadensis (after Hofmeister). A longitudinal section through the upper end of the endosperm <?« 

 and the lower end of the pollen-tube/, c c the archegonia, d their stigniatic cells, the left archegoniuin is fertilised, x rudi- 

 ment of the embryo (June 5), (X 300). £ part of the endosperm with an archegonium, the embryo of which v is already 

 further developed, p the pollen-tube (June 10) (X 200) ; C longitudinal section of a nucellus (June 15), kk nucellus, e e 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 

 pro thallium, 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 Coniferae. In the Abietineae 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 Y'lgi 

 indicated. 



354 and 355, which are transferred from the first edition, the caial-cell is not 



