292 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



random subsample was obtained from the cross 

 section. It was also shown that either of the two 

 ovaries could be used. The procedure routinely 

 used was to measure a random subsample from 

 the mid-section of an ovary. 



Table 4. — Analysis of variance of numbers of most ad- 

 vanced eggs from different parts of the ovary (albacore No. 

 42, Hawaii) 



Table 5. — Egg diameter frequencies of right and left ovaries 

 from the same fish (albacore No. 74, Hawaii) 



i 



Frequency 



Micrometer units ' 



10. 

 11. 

 12. 

 13.. 

 14. 

 15. 

 16. 

 17. 

 18. 

 19. 

 20. 

 21. 

 22. 

 23. 

 24. 

 25. 

 26. 

 27. 

 28. 

 29. 

 30. 

 31. 

 32. 

 33. 

 34. 

 35. 

 36. 

 37. 



Mm. 



40. 

 41. 

 42. 

 43. 



Sum. 



.167 

 .184 

 .200 

 .217 

 .234 

 .250 

 .267 

 .284 

 .301 

 .317 

 .334 

 .351 

 .367 

 .384 

 .401 

 .418 

 .434 

 .451 

 .468 

 .484 

 .501 

 .518 

 .534 

 .551 

 .568 

 .584 

 .601 

 .618 

 .635 

 .651 

 .668 

 .685 

 .701 

 .718 



Right 

 ovary 



259 



137 



124 



117 



107 



115 



82 



72 



75 



69 



51 



48 



54 



56 



45 



59 



40 



39 



47 



29 



32 



16 



15 



26 



27 



27 



18 



20 



19 



10 



6 



2 



Left 

 ovary 



1,847 



282 



147 



122 



101 



108 



93 



71 



64 



75 



64 



51 



44 



43 



55 



51 



46 



32 



30 



32 



32 



33 



19 



21 



32 



29 



28 



25 



19 



13 



8 



4 



1 



1 







1,776 



1 1 micrometer unit = .0167 mm. 



DEVELOPMENTAL STAGES OF THE EGG 



Eggs were classified as early developing, late 

 developing, and advanced. The descriptions are 

 based on formalin-preserved material. 



Early Developing 



This category includes the primitive eggs found 

 in all ovaries and eggs in the beginning stages of 

 development. The primitive eggs vary from 

 about 0.01 to 0.13 mm. in diameter, possess rel- 



atively large nuclei, and are transparent. In 

 early development the eggs increase in size and 

 become semi-opaque from deposition of yolk 

 granules. The maximum diameter of eggs in the 

 early developing stage is about 0.4 mm. 



Late Developing 



In this stage, the eggs are completely opaque 

 from the heavy accumulation of yolk granules. 

 They now range from 0.4 to about 0.8 mm. in 

 diameter. 



Advanced 



Distinct changes occur in the eggs as they 

 approach ripeness. They lose then opacity and 

 become semitransparent; the nucleus cannot be 

 detected at this stage, and a conspicuous golden- 

 yellow oil globule appears. These advanced but 

 not fully ripe eggs range from about 0.7 to 1.0 

 mm. in diameter in the most advanced sample 

 available for study. 



CLASSIFICATION OF OVARIES 



The ovaries were classified into three catego- 

 ries of relative maturity, early developing, late 

 developing, and advanced, according to the stages 

 of development of the largest eggs. In this classi- 

 fication, the early developing category included 

 the thin ribbonlike ovaries from sexually imma- 

 ture fish and ovaries from the larger adult fish 

 which showed no signs of egg development beyond 

 the early stage. The other two categories, on 

 the other hand, included only ovaries from adult 

 fish (fig. 3). 



As an example of the classification, a frequency 

 distribution of egg diameters from a fish classed 

 as having late developing ovaries (fig. 5) is shown. 

 In addition to the mode of largest eggs centering 

 at 0.63 mm., other groups of eggs are evident. 

 There are large numbers of early developing eggs 

 less than 0.4 mm. in diameter, and there is evi- 

 dence of a second group of late developing eggs, 

 one with a mode at 0.43 mm. Both groups of 

 late developing eggs were opaque, characteristic 

 of this stage. 



An advanced ovary (fig. 6) has a mode of semi- 

 transparent eggs centering at about 0.86 mm. In 

 addition there is one or more groups of late de- 

 veloping eggs between 0.4 and 0.6 mm., possibly a 

 less developed group at about 0.33 mm., as well as 

 the usual large numbers of early developing eggs. 



