THE AMERICAN LOBSTER. 
57 
The very fresh eggs can be usually detected by examination with a hand lens. 
The transparent egg capsule closely invests the yolk, which then presents a uniform, 
linely granular texture. The external segmentation of the yolk follows in twenty to 
twenty-five hours after oviposition, and the large yolk-segments can be easily distin- 
guished by the naked eye. At the close of this process, or after the invagination has 
begun, the living egg, when examined with a low power, resembles the fresh egg, 
excepting that the yolk has now a coarser and more irregular texture. The embryo is 
distinctly marked off in the egg-nauplius stage in about ten days, and when from 
twenty-six to twenty-eight days old the eye pigment can be seen at the surface. 
THE HATCHING OF THE EGGS. 
THE HATCHING OF LOBSTERS AT WOODS HOLE. 
We have seen that the period of incubation or fosterage lasts from ten to eleven 
months in the case of the summer eggs. As yet nothing is known about the hatching 
of the fall and winter eggs. The bulk of the eggs which are taken for the Woods Hole 
hatchery complete their development in the McDonald jars in June, as shown in the 
following table : 
Table 19. — Time of collection and hatching of the eggs of the lobster at the United States Fish Commission 
station, Woods Hole, Massachusetts; compiled from records of the station. 
Time of collection of tlie eggs. ' 
Hatching begun. 
Hatching 
ended. 
Time of hatching of 
majority of eggs. 
1890. Apr. 16 to June 13; majority taken 
May 17 
June 23 
June. 
in May. 
1891. Apr. 28 to Juno 29 
May 25 (eggs taken Apr. 28) . 
June 15 
June. 
1891-1892. Dec. 1, 1891, to Apr. 28, 1892. . . 
May 30 (eggs taken Apr. 25) . 
June 29 
June. 
1893. Apr. 19 to June 26 
June 15 
July 15 
June 15 to 30. 
These results agree with what takes place in nature when the lobster is permitted 
to keep her eggs for the full time. The eggs from several lobsters are usually placed in 
a single jar, and the jars are replenished while the hatching goes on. 1 The dates in 
the second and third columns of table 19 therefore indicate the general range of the 
hatching period, not that of the hatching of a single brood. 
Lobsters with light eggs, or eggs of the previous summer, were last caught in 
Vineyard Sound and vicinity in the summers of 1890 to 1893, at the following dates: 
1890, July 9. One female lobster taken in Woods Hole Harbor with eggs hatching; several hundred 
eggs not yet hatched. 
1891, July 16. Six female lobsters, with nine-tenths of the eggs hatched, taken at Menemsha. On 
July 11 a lobster was taken at that place with eggs in process of hatching, and on June 
30 two lobsters with old eggs were caught in Woods Hole Harbor. In one of these the 
eggs had begun to hatch ; in the eggs of the other there was still considerable unabsorbed 
yolk. 
1892, June 28. Four lobsters with old eggs were taken. 
1893, June 30. No lobsters with old eggs were taken at Menemsha after June 30. At this time they 
had in the past few days obtained 16 lobsters with old eggs, and in half of these the eggs 
had meantime hatched. 
1894, July 14. A lobster was brought from Menemsha, having been caught some time before, with eggs 
about four-fifths hatched out. 
‘The temperature of the water in the hatching jars in summer is about one degree higher than 
that of the water outside. 
