No. 463.] STUDIES ON PLANT CELL.— VI. 459 
somes is reduced with the germination of the sexually formed 
cell so that the protoplasm returns at once to the potentialities 
of the gametophyte. It is quite possible that the four zoó- 
spores produced from the oóspore of (Edogonium and the four 
nuclei found in the germinating zygospores of the desmids and 
Spirogyra may indicate divisions concerned with reduction 
phenomena similar to those in the tetraspore mother-cells of 
Dictyota (which may also be expected in the tetraspore mother- 
cell of the red algae) and in the spore mother-cell of the higher 
plants. ! 
For these reasons we seem to be justified in taking a critical 
attitude towards the accounts of chromosome reduction at game- 
togenesis among the thallophytes. The logic of the situation 
would lead us to expect that every sexual act gives a doubling 
of the chromosomes and an impulse towards the development 
of a sporophyte phase in plants which must be worked off before 
the protoplasm is in condition to reproduce the parent gameto- 
phyte. Reduction phenomena should follow then every sexual 
act. If it takes place immediately with the germination of the 
sexually formed cell there is of course no sporophyte generation. 
Because the conception of the sporophyte generation with reduc- 
tion of the chromosomes at sporogenesis is so clearly established 
in higher groups, those investigators who claim reduction phe- 
nomena at gametogenesis must expect their views to be severely 
scrutinized and accept the responsibility of presenting very clear 
and convincing proof of their conclusions. The author does 
not think that this evidence is supplied in satisfactory form by 
any investigation so far. 
2. FERTILIZATION. 
n IV of these “Studies” we described the most 
important phenomena of fertilization under the caption “ Sexual 
Cell Unions and Nuclear Fusions." It will not be necessary to 
discuss the facts of the phenomena in detail again. This account 
will take up the more theoretical aspects of the events of ferti- 
lization and their relation to other critical periods of ontogeny. 
Plants are in complete agreement with animals in the follow- 
In Sectio 
