56 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 

 Table 17. — The rate of development of the embryo at Woods Hole. 



No. 



D.iy. 



Hour. 



Tempera- 

 ture of 

 water. 



Age stage of development. Remarks, 

 of egg. 6 



Id) 

 1(2) 

 1(3) 

 1(4) 

 1(5) 

 1(6) 



1 (7) 

 1(8) 



1(9) 



2 (1) 



2(2) 



2(3) 

 2(4) 

 2(5) 

 2(6) 



1890. 



July 30 

 ...do... 

 ...do.... 



July 31 

 ...do..-. 

 ...do... 



Aug. 1 



Aug. 2 



Aug. 3 



1889. 

 July 11 



July 12 



July 13 

 July 14 

 July 18 

 July 19 



1.45 p.m. 



6.00 p.m. 

 10.00 p. m. 

 10.00 a. m. 



2.00 p.m. 



6.00 p.m. 



9.30 a.m. 



12.00 ni. 



11.00 a.m. 



5.30 p.m. 



9.30 a.m. 



1.00 p.m. 

 5.45 p.m. 

 9.50 a. m. 

 12.20 p.m. 



°F. 

 72 

 72 

 72 

 72 

 72 

 72 



72 



72 



72 



68 



68 



69 

 69 

 68 

 68 



Hours. 

 8(?) 

 121 

 16J 

 281 

 32J 

 36i 



5Tolk unsegmented 



...do 



2 to 4 cells present. 



do 





Segmentation of yolk . 

 rlo , ....' 



Few eggs only, with yolk unsegmented. 



Very few eggs still with yolk uhseginented. 



Several stages of yolk segmentation, some 

 eggs with about 30 segments ; others with 

 very small and numerous cells; in a few 

 .egg's yolk still unsegmented. 



Majority of eggs with at least 160 segments ; 

 some with irregular segmentation; some 

 with yolk non-segmented. 



Majority of eggs with periphered layer of 

 very small cells ; rarely an egg with unseg- 

 mented yolk. 



Majority of eggs in this stage. 



Late stage, about equivalent to 1 (7) above ; 



cells not quite superficial. 

 Protoplasm generally at surface, and cells 



most numerous on one side of egg. 



Pit at surface. 



Depression on surface very marked. 



Nauplius embryo not yet outlined. 



do 



51J- 



77| 

 100J 



do 



do 





Segmentation of yolk, 

 do 



16 h 



43£+ 

 72| + 

 1601+ 

 174|-t- 





do 



. do - - 



do 





Table 18. — Bate of development of the embryo at Woods Role. 



No. 



3 (1) 



3 (2) 



3 (3) 



3 (4) 



3 (5) 



3 (6) 



3 (7) 

 3 (8) 



3 (9) 



3(10) 



3(11) 

 3(12) 

 3 (13) 

 3(14) 



3(15) 

 3(16) 

 3(17) 

 3(18) 

 3(19) 

 3 (20) 



Day. 



Hour. 



Tempera- j 

 ture of Age of < 

 water. 



1890. °F. 



July 9 j 3.45 p. m. ' 71 



July 11 I 12.45 p. m. 69 



July 15 ' 10.30 a. m. 69 



July 17 

 July 22 



..do. 



July 27 

 July 29 



Aug. 3 



Aug. 12 



Sept. 

 Oct. 



Nov. 

 Dec. 



1891. 

 Jan. 

 Feb. 

 Mar. 

 Apr. 

 May 

 June 



12 m. 



12 m. 



o p. in. 

 10.30 a. m. j 

 12.30 p. m. | 



71 » 

 70 



70 



71 



72 



Days. 

 8 



10 

 14 



16 



21 



26 



28 



33 



42 



61 

 91 

 122 

 152 



183 

 211 



242 

 273 

 303 

 334 



Stage of develop- 

 ment. 



Remark* 



llrs. 



3(0 



31 

 31 



24 



21 

 8J 



1C1 



Invagination . 

 Egg-nauplius 

 ....do 



....do 



Post-nauplius 



Pit at surface very conspicuous. See cut 25. 

 In some eggs, second antennae not budded. 

 Second antennas bifid; thoracic abdominal 



fold formed . See cut 31. 

 Late egg-nauplius. See cut 32. 

 4 to 5 pairs of post-mandibular appendages; 



tip of "tail" conspicuously forked; optic 



disks lobular. Cut 34. 

 Optic lobes very large; telson overlaps 



brain; 6 or 7 pairs of post-mandibular 



appendages ; antennae and telson tipped 



with rudimentary setae. 

 Telson reaches base of optic lobes. 

 Eye pigment present for about 24 hours. 



'Cut 35. 

 Eye-spots crescentic or semicircular; telson 



overlaps bases of optic lobes. 

 Eye-spots oval; telson considerably behind 



optic lobes. 

 See drawing, cut 36. 



See drawing, cut 37. 



See drawing, cut 38. 



Larvae hatching out. 



The lobster (No. 3, table 18) which laid eggs about July 1, 1890, was kept under 

 observation at the Fish Commission station at Woods Hole for a period of 11 months 

 or 334 days, until -Tune, 1891, when, as we see, the eggs had begun to hatch. Under 

 natural conditions the period of incubation of the summer eggs at Woods Hole is 

 nearer 10 months— (from July 16th- August 15 to May 15-June 15). 



