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Lloyd Williams . — Studies in the Dictyotaceae . 
round the newly liberated eggs in preference to the others, probably 
in consequence of a chemotactic attraction. 
5. When an egg has been fertilized the nucleus generally has within it 
a second smaller (male) nucleolus. Later on thirty-two chromosomes appear, 
but the two nucleoli are still present. There is at first a single centro- 
some which divides into two ; as the two separate the two spindle-cones 
also diverge, till ultimately they form a normal spindle. 
6 . When an egg has not been fertilized the nucleolus breaks up 
into chromosomes ; leaving no residual nucleolar matter to be extruded 
into the cytoplasm as occurs in other mitoses. The mitotic figure is 
very irregular and multipolar ; there is no nuclear membrane, and a cluster 
of nuclei is formed each containing sometimes one, sometimes several 
chromosomes. These separate into two or more groups, and partition 
walls are formed between them. The process may go on a little further, 
but very soon it stops and the germlings die. 
7. When normal germination is compared with parthenogenesis we 
find that the entry of the antherozoid into an egg produces the following 
results : — 
(a) It causes a centrosome and radiations to appear in the cytoplasm. 
(h) Sixteen additional chromosomes are introduced into the nucleus. 
(c) The metabolism of the nucleus is far more active, as is shown 
by the greater amount of nucleolar matter and the increased size of the 
chromosomes in the prophase stage. 
(d) In the mitosis it introduces a directive influence which is 
completely absent from the parthenogenetic figure. This prevents the 
scattering of the chromosomes and the consequent formation of a large 
number of nuclei. 
(e) It prevents the early disappearance of the nuclear membrane. 
