208 
Agnes Robertson. 
IV. —The Archegonia. 
Early in August the young archegonia have begun to develope. 
Figs. 4 and 5 shew an ovule containing one with a two-celled neck. 
On August 12th, six days later, an archegonium was found with one 
of its two neck-cells undivided, and the other with two daughter- 
nuclei at the poles of a spindle (Figs. 6 and 6a). The number of 
neck-cells in the mature archegonium seems to be somewhat vari¬ 
able. Figs. 7 and 8 shew transverse sections of necks which are 
respectively four and six-celled. There is normally only one tier, 
but occasionally one cell may divide by a periclinal wall as shewn 
in longitudinal section in Fig. 9. The number of archegonia in 
each ovule is two, three or four, three being the number most 
commonly met with (Fig. 10), and I have once seen as many as 
five. In Taxus, Jiiger 1 speaks of five to eight as the usual number. 
The archegonia are usually placed at the top of the prothallus, but 
three times I have found one in an abnormal position quite low 
down. I have once found a double archegonium resembling those 
several times observed by Miyake in Picea.- 
The jacket cells are rather richer in protoplasm than their 
neighbours and have conspicuous nuclei (Fig. 11), but 1 have not 
observed any pits in their walls, or transference of nuclear matter 
into the archegonium as described by Arnoldi 3 for various Conifers. 
In late stages the archegonia become buried some little distance 
beneath the surface of the prothallus, recalling Jager’s description 
of Taxiis. 4, 
Of half-a-dozen ovules gathered on August 20th, five shewed 
archegonia with the nucleus of the central cell undivided (Fig. 11). 
The sixth contained three archegonia, of which two shewed the 
nucleus of the central cell in the act of dividing to produce the 
ventral canal and egg-nucleus. One pollen-tube had entered the 
nucellus, but had not yet reached the embryo-sac. It ran nearly in 
the plane in which lay the archegonium which was the more 
advanced in the division of its nucleus. The chromosomes of the 
two daughter-nuclei were slender and V-shaped (Fig. 13), recalling 
Coker’s figure of this stage in Taxodium .* It is remarkable that in 
1 L. Jager. Loc. cit. 
2 K. Miyake. “ On the Development of the Sexual Organs and 
Fertilisation in Picea excelsa .” Annals of Botany, Vol. 
XVII., March, 1903. 
3 W. Arnoldi. “ Was sind die Keimblitschen.” Flora, 1900, p. 194, 
4 L. Jiiger. Loc. cit. 
4 W. C. Coker. “ On the Gametophytes and Embryo of Taxo¬ 
dium.” Bot. Gaz., July, 1903, Fig. 87. 
