Gates . — Somatic Mitoses in Oenothera . 
1003 
Canada balsam, and permanently unchanged as regards the arrangement 
of its fibres and the attachment of the chromosomes. Even were it not 
already abundantly evident from other sources, one could not fail to be 
convinced by this simple observation that the spindle is a structure more 
stable than the rest of the cytoplasm, and that the chromosomes are 
definitely attached to the spindle fibres. 
In this connexion certain observations of Lillie (’ 08 ) on the eggs of 
the annelid worm, Chaetop terns , are worth citing because they lead to 
exactly the same conception of the relations between spindle and cyto- 
plasm. Eggs of Chaetop terns suspend their maturation processes in the 
metaphase of the first reduction division to await the entrance of a sperm, 
the spindle being attached by one pole to the periphery of the egg. If 
eggs in this condition be centrifuged, the spindle with its attached chromo- 
somes is frequently torn loose and displaced by the centrifugal force to one 
side of the egg. But the chromosomes remain attached, though the spindle 
may be more or less distorted by too rapid centrifuging or by the impact 
of the heavy yolk globules thrown against it. It was further found that if 
such centrifuged eggs are afterwards fertilized and allowed to develop, the 
spindle migrates back to its original position in order to complete the 
maturation processes. 
Reduction Divisions (?) in Somatic Tissue. 
The primary purpose of the preceding account of normal mitosis in 
nucellar tissue was to afford a basis for comparison with certain cases 
which appear to represent actual reduction divisions in the same tissue. 
Two such cases were carefully observed which agreed in all essentials, and 
one of them is represented in Fig. 37. The cell containing this spindle 
occurred near the margin of the nucellus of an apparently normal ovule. 
Adjacent cells were in various stages of normal mitosis. As will be seen 
from the figure, this spindle was exceptionally large. Comparison with 
Fig. 38 shows it to be nearly as long, though not so broad, as the hetero- 
typic spindle, though the containing cell was not conspicuously larger than 
surrounding cells of the nucellus. The spindle is conspicuously larger than 
in normal nucellus cells such as are represented in Figs. 14, 16, 23-6. 
As regards the chromosomes, which are not all represented in Fig. 37, 
they could not all be determined with certainty, owing to the crowded 
positions occupied by some. But as far as could be determined, there were 
certainly two very clear pairs or bivalents in which the individual chromo- 
somes could be seen, one pair in which the two chromosomes appeared to 
be closely appressed or fused, two pairs less clear owing, apparently, to 
partial fusion, one other probable pair, one certainly single chromosome, 
and probably another single chromosome. This makes 14 chromosomes. 
The presence of the fifteenth could not be determined. 
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