140 Johnson. — On A rceuihobium Oxycedri . 
especially after staining with saffranin or picronigrosin, the 
two apical synergidal cells and the lateral oosphere were 
distinctly seen. The general outline of the ovarian papilla 
is not affected by the presence of the embryo-sacs ; there is 
no indication by lobes on the papilla of their occurrence in 
its interior. 
Each embryo-sac arises as a hypodermal cell which divides 
by a horizontal wall into two ; the upper and smaller cell is 
the primary tapetum-cell, and divides into two by a vertical 
wall. The lower one is the mother-cell of the embryo-sac, 
and after having cut off from its lower end two small cells by 
horizontal walls, it enlarges into the embryo-sac. The nucleus 
of the uninucleate stage of the embryo-sac is very large and 
pronounced (Figs. 4-5). Whether each embryo-sac should be 
regarded as derived from a special hypodermal archesporium, 
or as a fully developed cell of a hypodermal multicellular 
archesporium common to the two embryo-sacs, will be made 
clear, it is hoped, by what is said further on. 
The flowers were seen first in September, by Reinaud. 
Pollination occurs towards the end of September or the 
beginning of October, and judging from analogy with 
Viscum album and Loranthus eitropaeus , fertilisation does 
not take place till the following spring. The thin pollen- 
tube passes down the stylar canal and penetrates into the 
ovarian papilla at its summit, passing into it for a certain 
distance towards the apex of the embryo-sac and resting there 
till the beginning of vegetation in the next year. It seemed, 
on first consideration, that the interval of time between polli- 
nation and fertilisation gave some support to the suggestion of 
Marshall Ward 1 that the effect of parasitism is to degrade 
sexual organs and their function ; that, indeed, there might be 
some subtle connection between fertilisation and the forma- 
tion of the seeds in parasite and host in the case of Arceu- 
thobium , which grows on Pinus 2 or on Juniper us , the two 
genera of the Coniferae in which a year intervenes between 
1 Marshall Ward, in Q. J. M. S. xxiv. 
2 Pinns brachyptera , P. Banksiana , Jmiiperus communis , J. Oxycedrus. 
