KING: CYTOLOGY OF ARAIOSPORA PULCHRA. 
239 
Stevens accepts Strasburger’s theory that there is a difference 
in the cytoplasmic nature of the sexual cells and finds it strongly 
confirmed in his studies of the genus Albugo. This theory of fer¬ 
tilization, it will be recalled, assumes that the oosphere is rich in 
trophoplasm, the food-supplying cytoplasm, and poor in kinoplasm or 
active cytoplasm, and that precisely opposite conditions obtain in 
the antheridium. Such a theory seems extremely reasonable in 
view of the fact that it appears to have general confirmation in 
the sexual cells of both plants and animals. For example, egg 
cells are usually large, passive and have a rich food supply; on 
the contrary, the sperm cells are almost invariably small and 
extremely active. According to Stevens (:01b), as the oogonia 
develop, the oosphere becomes rich in trophoplasm and the kino¬ 
plasm migrates outward and is cut off with the periplasm. The 
peripheral movement of the nuclei is accounted for on the ground 
that they “ pass to the periphery to rid themselves of superfluous 
kinoplasm, possibly to prevent parthenogenetic development of the 
oosphere.” Stevens, furthermore, expressly states that this migra¬ 
tion cannot be accounted for on the grounds of phylogeny, atavism, 
or wall building. 
To the writer such an explanation of nuclear migration seems 
entirely inadequate. Why should the periplasm be the general 
recipient of the kinoplasm of the oosphere when little is needed 
there and much will be demanded in the development of the 
oospore? Furthermore, the kinoplasm, introduced with the sperm 
is often entirely too little in amount to furnish the fertilized cell 
with sufficient active cytoplasm. The facts set forth in the investi¬ 
gation of Araiospora bear on this point and give ground for a" differ¬ 
ent interpretation of nuclear migration. It will be recalled that there 
is a nuclear migration in Araiospora early in the history of the oogo¬ 
nium before there are evidences of a differentiation into oosphere 
and periplasm. It may furthermore be recalled that these nuclei 
become isolated and are cut off later with a limited amount of peri¬ 
plasm. It has also been pointed out that these nuclei function at 
once, possibly even before fertilization, in laying down cell walls on 
at least portions of the surface of each peripheral cell. It is entirely 
probable, therefore, that the periplasm contains some kinoplasm, and 
the migration of nuclei and kinoplasm, if the latter migrates, is at the 
present time, at any rate, for the purpose of building the walls of 
