Shaw , — The Fertilization of Onoclea, 281 
completion of this account of fertilization. The quiescent 
period may be partly or entirely due to imperfect nutrition, 
and if so it is likely to vary in different closely related 
species, and in the same species under different conditions. 
We have found the period to be long in three cultures and 
two species. 
Many of the prothallia used for the present study probably 
bore, in addition to the eggs fertilized at the recorded times, 
others which matured later and were then fertilized. This 
might have been prevented by draining the prothallia, as 
was done with those which were fixed during the next 
season. This may be accomplished when the prothallia are 
removed from the soil to be fertilized, as must be done if 
they are to be carefully examined, by placing them on moist 
filter paper in a moist chamber. It will be desirable not 
only to prevent the fertilization of archegonia which mature 
later, but also any which have matured earlier than the 
beginning of the experiment. The most trustworthy account 
of fertilization will be based on eggs on prothallia on which 
only one egg is fertilized and that at maturity. Such 
specimens can be obtained by fertilizing large numbers of 
prothallia and selecting after ten minutes those on which 
only one archegonium opens and attracts spermatozoids. 
Summary of Results. 
j. The body of the free spermatozoid consists of a long 
corkscrew-shaped nucleus which stains homogeneously, and 
a lateral band of cytoplasm which extends a short distance 
in front of the nucleus. 
2. The sperm-nucleus enters the egg-nucleus before it 
changes in form or visible structure. 
3. Within the egg-nucleus the chromatin-granules of the' 
sperm-nucleus slowly separate as the meshes of the linin- 
network slowly enlarge. 
4. Throughout the process of fertilization the female 
nucleus is in the resting condition. 
