Actinostrobus pyramidalis , Miq. 341 
connexion may mean only the parallel development of the two groups ; it 
very probably does ; but it seems of interest to note a likelihood that in 
certain respects the Callitrineae have perhaps developed in a similar direc- 
tion to the Gnetales, and that to a somewhat less extent the Cupressineae 
have also done so. 
The general question of Conifer classification is to be discussed in 
another place, and no further reference need be made to it here. 
7. Summary. 
1. About three months elapse between pollination and fertilization in 
Actinostrobus. 
2. Each microsporophyll bears usually three sporangia. 
3. The mature pollen-grains are uninucleate. 
4. From six to twelve (usually nine) ovules are borne in each female 
cone. 
5. A single megaspore mother-cell is formed in the nucellus, and no 
spongy tissue is organized. 
6. Archegonia are formed from the alveoli, after the cutting off of some 
small cells at base and apex, and are deep-seated, a group of twenty-five 
to thirty being found abutting on the lower end of each pollen-tube, which 
reaches about half-way down the prothallus. 
7. Large secretory cavities are found in the tissue of the integument, 
alternating with the wings. 
8. The older cells of the prothallus are generally binucleate or four- 
nucleate. 
9. The male gametophyte agrees very closely with that of Cupressineae, 
but the two male cells appear to be enclosed within a mother-cell wall when 
first formed. 
10. The two male cells fertilize two approximately adjacent arche- 
gonia. 
11. In fertilization the sexual nuclei are practically alike in size and 
structure. 
12. Wall formation in the proembryo occurs during, and following, the 
transition from the binucleate to the four-nucleate condition (i. e. earlier 
than in most Pinaceae), and the proembryo completely fills the arche- 
gonium. 
13. Most of the cells of the mature proembryo give rise, by a very 
unequal division, to a suspensor and an embryo initial. 
14. The first two division walls in the embryo initial are vertical. 
15. Further development of the embryo is the same as in other 
Conifers. 
