No. 463.] STUDIES ON PLANT CELL.— V1. 463 
ments, substances of great service, although possibly not abso- 
lutely necessary to the successive metabolic processes which 
characterize growth and development. But the fact remains 
that we have in the chromosomes the only new morphological 
elements. And the progress of research seems ever to 
strengthen the general view that in the chromosomes are 
contained the directive rudiments of development and that 
they are the bearers of hereditary principles. Nuclear studies 
on apogamous forms will certainly prove of great interest in this 
connection. We have reason to expect some very important 
results from thorough cell studies on apogamy and apospory. 
The best developed theory of fertilization in plants is that of 
Strasburger and a statement of his views should precede any 
comments of other authors. Strasburger has written much on 
the phenomena of fertilization ; important considerations may be 
found in his papers of '94a, b, '97c, : 00a, b, : O1, and :04a. 
Strasburger points out that the protoplasm of the egg is pre- 
dominately trophoplasmic in character because of the propor- 
tionately very large amount of cytoplasm with granular inclusions 
that are evidently food material or the products of metabolism. 
On the other hand the cytoplasm of the sperm contains rela- 
tively little trophoplasm and much kinoplasm, especially when 
the sperm is a ciliated cell with a large blepharoplast. As 
Strasburger conceives kinoplasm to be the active substance of 
spindle formation, he concludes.that the sperm might bring to 
the well nourished egg, rich in trophoplasm, the substance neces- 
sary to start the mechanism of mitosis. In its broad aspects 
this view is very similar to the celebrated theory of Boveri, 1887, 
that the spermatozoón supplied the animal egg with the centro- 
some which is conceived as necessary to start mitotic processes 
and that the egg is powerless to divide before fertilization 
because it lacks such a structure. 
Another feature of Strasburger's views (advanced in his paper 
of :oob) appears to have grown out of the discovery of the so 
called “double fertilization ” in the embryo-sac and other nuclear 
fusions whose sexual significance is not clear, together with the 
phenomena of parthenogenesis as produced experimentally in 
many studies of recent years. Strasburger considers that two 
