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PACIFIC SCIENCE, Vol, XV, April 1961 
cuse watch glass; the eggs were teased from the 
ovarian tissue with dissecting needles; the egg 
diameters were then measured with an ocular 
micrometer at X 24. Many of the eggs were 
oblong, probably because of unequal pressure 
of adjacent eggs at the time of preservation. 
Instead of measuring the greatest or least diam- 
eter, the eggs were moved into position by mov- 
ing, but not turning, the watch glass on the 
micrometer image which remained fixed in a 
horizontal position. This method reduces the 
possibility of bias but has the disadvantage of 
increasing the spread of modal groups on graphs 
of egg diameter measurements. 
Graphs of the egg diameters of ovaries from 
9 adult female manini are shown in Figure 8. 
These graphs do not show any definite sequence. 
Graph C, of a 15 mm. ovary from a female 
taken on January 2, for example, portrays the 
egg diameter pattern of an immature but matur- 
ing ovary. No graphs were made of egg diam- 
eters of ovaries from adult fish taken in August 
because the fish have only primordial eggs about 
1 to 3 micrometer units (.035 to .105 mm.) in 
diameter except for those in which larger eggs 
are being resorbed. The relative size of the 
group of primordial eggs was estimated only for 
the ovary graphically illustrated in A. 
Except for the immature gonad of C, all of 
the ovaries display a mode of egg size centered 
on about 10 to 12 micrometer units in diameter. 
This prompted the examination of samples of 
eggs from 54 ovaries taken from female fish 
throughout the year (more, however, from 
mature females during the spawning season). 
Sufficient eggs from each ovary were measured 
to determine the presence of obvious modal 
groups. A definite mode at from 9 to 12 mi- 
crometer units in egg diameter occurred in 46 
of the ovaries, 15 to 35 mm. in length, from 
fish caught from September 15 to July 21. The 
median of this mode of 38 of these fish appears 
to lie between 10 and 12 micrometer units. In 
the ovaries of 8 fish, the median lies between 
about 9 and 10 units. One of these fish is the 
only running ripe female of the 54 examined. 
The remaining eight fish lack an intermediate- 
size mode; all of these have small gonads. No 
specimens were found among the 54 females 
with a group of eggs which have an average 
diameter greater than 12 units but less than the 
20 to 21 unit average size of ripe eggs. Also, 
when checking for ripe females among the 3,863 
adult manini of Table 6, the eggs pressed from 
the body cavity of few, if any, of these were of 
a size between that of the usual mode and the 
ripe egg mode. It is expected that such a size 
would be extruded with moderate pressure on 
the abdomen of the fish, since eggs of about 10 
micrometer units (0.35 mm.) are frequently 
forced out. Eggs as large or nearly as large as 
completely ripe eggs, but in which small opaque 
white regions were visible, were seen almost as 
often as the ripe, perfectly transparent eggs. 
These can not be fertilized, and females contain- 
ing them were not considered among the ripe 
fish previously discussed. The failure to find a 
mode of eggs intermediate in size between about 
10 and 20 micrometer units suggests that eggs 
maturing from the former modal group (the 
eggs of which are opaque) do so rapidly. Per- 
haps the enlargement is essentially a process of 
hydration. 
In view of the finding of so few female ma- 
nini with fertilizable eggs during the season, it 
is further believed that the ripe eggs are not 
retained very long in the ovary. Admittedly a 
change in behavior of ripe females might in- 
fluence the frequency with which they enter 
traps ( a possible cessation of feeding, however, 
would not seem to affect the rate of entry, for 
the traps, as mentioned, are unbaited). Also, 
confinement in the traps might affect the mat- 
uration of the eggs. 
If, however, it is assumed that ripe eggs are 
held within a female no longer than 1 day on 
the average, and 43 ripe female fish is the num- 
ber that would be present in truly random sam- 
ples of the population equal in size to the ones 
taken, then the small number of ripe females 
actually constitutes an indication that every adult 
female spawns once each lunar month. Since 
the lunar month is 29.53 days, only about one- 
thirtieth of the females sampled from the pop- 
ulation during the spawning season would be 
ripe. As mentioned, 3,863 adult manini were 
examined during the 1953-54 season, an esti- 
mated one-third of which, or 1,288, were fe- 
males. One-thirtieth of 1,288 is 43, precisely 
the number of ripe females which were found. 
