26 
BULLETIN OF THE BUREAU OF FISHERIES 
in size with the fish taken inside the river at Warrendale and which are undoubt- 
edly mature. There can be no question that the fish with the smaller eggs would 
not have matured during the year in which they were caught. The details of the 
distribution of egg sizes among the various age groups in these two collections 
can be seen by referring to Tables 17 and 18, on page 81. 
Secondly, if it be true that the variations in egg size form a valid criterion of 
the degree of maturity, it should be found that among the fish taken in the ocean 
some of the age groups will contain both individuals with large eggs and others 
with small eggs. Those with large eggs are destined to mature dui^ing the year in 
which they were caught and those with small eggs would not have matured for at 
least one more year. This condition will inevitably result from the fact that the 
fish do not all mature at the same age. Considering the fish of a single age group, 
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Fig. 3— Distribution of egg sizes among females in their tliird year, ocean nuclei, taken at 
Monterey, June 19 to 21, 191S 
say three years with ocean nuclei, whidh may be found together in the ocean, some 
of them will mature during the year as 3-year fish while others will not mature 
for another year, as 4-year fish. If the size of the eggs forms such a criterion as 
is claimed, it should be possible to segregate these two categories on the basis of 
egg sizes. It has been found possible to do this more or less clearly in a number 
of the collections that have been studied. For example, in Table 18 (p. 81) it 
may be seen that individuals with large eggs (maturing) and those with smaller 
eggs (immature) are to be found among the fish in their third year with scales having 
nuclei of the ocean type. The same thing is true of the fish in their fourth year 
with scales having nuclei of the stream type, given in the same table. Similarly, 
in the collection at Monterey (June 19 to 21, 1918) the 3-year fish with ocean 
nuclei are well separated into two groups on the basis of egg size (Table 25, p. 87). 
The frequency distribution in this last-mentioned collection is shown in Figure 3. 
