GROWTH AND AGE AT MATURITY OF THE PACIFIC RAZOR CLAM 
225 
accurately. For the sake of simplicity this intermediate stage has been called the 
" second stage of immaturity." It was first thought that the second stage of im- 
maturity, as here explained, was a transient phase preceding complete maturity 
by a few weeks. Careful study, however, showed that this intermediate stage per- 
sists after the mature clams have spawned. Small egg strings or sperm-bearing 
masses are present in unchanged condition in late summer. Female clams have 
small elongate eggs, which do not change during the season. For these reasons it 
appears that those individuals passing through this stage remain in the same condi- 
tion for the year prior to maturity. It is not known whether the reproductive 
products are held over the following winter or are resorbed. 
Assuming that the stage of maturity is accuratelj^ determined in all cases (282 
clams examined), the facts seem complicated. For the sake of clearness Figure 16 
has been prepared from the data given in Tables 6 and 7. From it the process of 
coming into maturity is shown from the standpoint of age of the specimens. At 
Cordova all of the specimens examined in their second year were immature. In 
the next class a few (5.3 per cent) had become completely mature, and the same 
number had developed onh^ partially — that is, had reached the second stage of 
immaturity. The following year class showed a few still immature and the mature 
ones of the former year still present, with their number increased by the addition 
of those in the second stage of immaturity of the former year. It is also shown 
that about 80 per cent of the fourth-year class passed out of the immature state, 
going into the two advanced divisions in the proportion of about 3 to 5, the smaller 
number becoming mature and the remainder advancing to the second stage of im- 
maturity. No immature clams were found in the fifth-year class; 80 per cent were 
mature and 20 per cent were in the second stage of immaturity. This last figiire is 
larger than the number of immature of the preceding year, but does not necessarily 
show that some individuals remained in the second stage of immaturity more than 
one year. 
Table 6. — Sicickshak leach: Size of clams in different stapes of maturity 
Length in centimeters 
Age 
3 
4 
5 
Imi 
Imj 
M 
Imi 
Imz 
M 
Imi 
Im2 
M 
7.5 
22 
17 
36 
28 
12 
3 
8.0 
8.5 
7 
19 
21 
8 
1 
9.0 
1 
3 
2 
2 
9.5 - 
5 
15 
5 
1 
2 
3 
7 
3 
2 
10.0 _ 
11 
15 
18 
14 
8 
11. 16 
10.5 
1 
2 
1 
3 
11.75 
11.0 -- 
11.5 
12.0 
Medians 
8. 78 
9. 55 
10. 30 
9. 83 
10. 32 
Medians (total) 
9. 25 
10.91 
11. 75 
