60 MARCUS M. HARTOG. 
nay, in some cases the oosperm or zygote in each archegonium 
by early fission produces four embryos; and yet only one 
embryo ripens in the seed. In Angiosperms the proportion of 
matured seed to ovules and carpels varies very greatly. In 
Anemone several ovular origins are formed, but only one 
ovule attains full size in each carpel; in Drupacez two 
ovules are present, but only one ripens into a seed, the excep- 
tion constituting the well-known “ Philippina”’ of stone-fruit. 
The one-seeded Acorn is the outcome of an ovary with three 
biovulate carpels. 
The fate of the central procarpia or oogonia of Corallina, 
reduced to the position of mere agents for the transmission of 
the male substance, finds a parallel in the peculiar transforma- 
tion undergone by the showy sterile peripheral flowers in the 
inflorescence of Viburnum, Hydrangea, and some Com- 
posites, into mere signboards, attracting the insects whose 
visits fertilise the less conspicuous central flowers. The petals 
of many flowers (e.g. Ranunculacez) are merely the 
degraded sterile outer stamens. 
In the animal world severe competition exists between 
embryos in those Molluscs which have numerous eggs in a 
single capsule. Here the first larvee to hatch out in the veliger 
stage eat up their more tardy brothers and sisters. 
We may note that some of the nuclei produced by the 
zygote nucleus of the exconjugate Ciliate are rejection-nuclei, 
and fail to take any share in the life of its offspring. 
D. Summary of Gametogenic Processes. 
1. In many Protozoa the gametes are apparently ordinary 
individuals or swarmers, the product of normal fission or 
brood-formation. 
2. In many Phytomastigopods and Protophytes the gametes 
differ from ordinary zoospores in being produced by more 
rapidly repeated acts of fission or segmentation, and in their 
smaller size. 
