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, 

 finely granular texture. The external segmentation of the yolk follows in twenty to 

 twenty live hours after oviposition, and the large yolk-segments can be easily distin- 

 guished by the uaked 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 the eggs. 



Hatching begun. 



Hatching 

 ended. 



Time of hatching of 

 majority of eggs. 



1890. Apr. 16 to June 13 ; majority taken 

 in May. 



1891-1892. Dec. 1, 1891, to Apr. 28,1892... 

 1893 Apr 19 to June 26 



May 17 



June 23 



June 15 

 June 29 

 July 15 



June. 



June. 

 June. 

 June 15 to 30. 



May 25 (eggs taken Apr. 28) . 

 May 30 (eggs taken Apr. 25) . 







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 iu 

 Vineyard Sound and vicinity iu the summers of 1890 to 1893, at the following dates : 



1890, July 9. One female lobster taken in Woods Hole Harbor with eggs batching; several hundred 



eggs not yet batched. 



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 batching, 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 tbe other there was still considerable unabsorbed 

 yolk. 



1892, .Time 28. Four lobsters with old eggs were taken. 



1893, June 30. No lobsters with old eggs were taken at Menemsba after June 30. At this time they 



had in tbe past few days obtained 16 lobsters with old eggs, and in half of these tbe eggs 

 bad meantime hatched. 



1894, .July U. A lobster was brought from Menemsba. having been caught some time before, with eggs 



about fonr-hfths hatched out. 



1 Tbe temperature of tbe water in the batching jars in summer is about one degree higher than 

 that of the water outside. 



