45^ 



PHANEROGAMS. 



(lower) cell is thus formed, the central cell of the archegonium, and an upper small 

 one, lying next the embryo-sac from which the neck of the archegonium is formed \ 

 In Abies ca?iadensts this neck remains simple and unicellular, and elongates 

 considerably with the increase in size of the surrounding endosperm; but usually 

 the original cell which constitutes the neck divides into several cells which either 

 lie only in one plane (Figs. ^24 A, d, 325 /, ^), the ' stigmatic cells,' or form several 

 layers lying one over another (as in Abies excelsa and Pmiis Pinaster). Seen from 



Fig. 325. — Juniperus coMityiunis {after Hofmeister). / three archegonia cp close beside one another, in two of 

 them the fertilised embryonic vesicles is imbedded in the upper end, (Astigmatic cells,/ pollen-tube (July 28) (X300). 

 // a similar section, e e the endosperm, v v the pro-embryos ; /// lower end of one of the longitudmal rows of cells of 

 a pro-embryo with the rudmient of the embryo eb ; IV longitudinal section of the nucleus kk, e the endosperm, e' por- 

 tion of the endosperm that is broken up, p pollen-tube, cp the archegonia, v the pro-embryos (beginning of August) 

 (X80). 



above the neck appears to form a four-celled, or, in Abies excelsa^ even an eight- 

 celled rosette. The homology of the archegonium ' corpuscula ' with the arche- 

 gonium of Vascular Cryptogams, already established by the earlier investigations of 

 Hofmeister, is carried a step further by Strasburger, who discovered the formation 

 also of a canal-cell. He considers that the part of the protoplasmic contents of the 

 large central cell which lies immediately beneath the neck are separated from the 

 rest by division, and a small cell is thus formed shortly before fertilisation {i. e. 



^ Hofmeister (Vergleichende Untersuchungen, p. 129) gives a somewhat different account of the 

 origin of the archegonium [Germination, &.C., p. 410]. 



