II. The Ovule of Stangeria paradoxa. 295 
be mentioned in conclusion. Evidence was obtained that 
small accessory embryos 1 may be formed on suspensors which 
terminate in normal embryos, but the material did not permit 
of their detailed study. In one instance an embryo was 
found to have originated at the upper end of the archegonium. 
The suspensor, which was of considerable length, projected 
from the archegonium-neck into the depression at the micro- 
pylar end of the prothallus (Fig. 33), but the embryo borne 
on it had apparently disappeared. Probably the disappearance 
of the fluid filling the archegonial depression at the time 
of fertilization had arrested its growth. A small accessory 
embryo was present within the archegonium. 
The above description will have made evident the close 
general agreement in development of ovule, pollination, fertiliza¬ 
tion, and embryogeny, which Stangeria presents with other 
genera of Cycads. The phenomena observed in Stangeria 
may be briefly summarized:— 
1. Two ovules are developed on each sporophyll; they are 
situated one on either side of the short stalk and are not 
marginal, but borne on the morphologically lower surface. 
2 . The development of the ovule is similar to that of 
Ceratozamia , save that the mother-cell of the embryo-sac 
appears to attain a greater size before it undergoes division 
into three. The parts of the ovule (stalk, integument, nucellus, 
sporogenous group and megaspore) bear the same relations 
to one another as in Ceratozamia. 
3. At the time of pollination the prothallus fills the mega¬ 
spore, but archegonia are probably not present; the sporo¬ 
genous tissue is represented by a single persistent layer, 
possibly tapetal in nature ; the pollen-chamber is fully formed, 
but absorption of the tissue of the nucellus between it and 
the megaspore has not commenced. 
4. The pollen-tubes penetrate the nucellus as in Cycas and 
Zamia\ in the free end of each two spermatozoids are formed. 
1 Such accessory embryos are described in Macrozamia by Miquel, Nouveaux 
Materiaux pour la Connaissance des Cycadees, p. 18, PI. II, figs. 4 and 8 (Arch. 
Neerland., t. iii, 1868). 
