498 PROCEEDINGS OF THE NATIONAL MUSEUM.
vol.xxix.Fig.22. Viewfrom below of a high-arched 16-celled stage, showing 9 cells inthe first tier, 6 in the second, and 1 keystone, together with the large seg- mentationcavity.
23. Nearlynormal82-celledblastoderm.
24. Irregular27-celled blastoderm. Cells inthreetiers, blastodermthickestat loweredge.
25. Irregular28-celled stage. Cellsinthreetiers,blastodermhighestincenter.
26. Divided32-celledblastoderm, 14cellsin smaller, 18 in larger division, both restingonacommonprotoplasmicbasis.
27. Laterstage,with38cells,showingthegrowingirregularity ofthesegmenta- tion.
Plate VII.
28. Section through germdisc,5 hours inwater. Belowthe dotted line yolk andprotoplasmaremixed.
29. Section through germ disc, 11 hours and 20 minutes in water, showing formationofbuds.
30. Sectionthroughgermdisc262hoursin water.
31. Sectionthroughgermdisc36-48 hoursinpouch.
32. Sectionthroughcenterof1-celled stage likefig. 1, Plate V.
33. Section through 2-celled stage. Protoplasmic fibrilsatrightanglestothe planeof the furrow.
34. Stageof2cells, sectionthrougha-hoffig. 2.
35. Irregular 2-celled stage, section through a-h of fig. 3, showingvesicle at baseoffurrow.
36. Two-celledstage, furrowtakingform ofnarrowcleft.
37. Furrow of 2-celled stage formed by breaking down of walls of vesicles lyingina verticalseries.
38. Horizontalsectionthrough4-blastomerestage offig.4.
39. Stageof8cells, sectionthroughplane a-hoffig. 7.
40. Stageof8 into16cells, sectionthroughc-doffig. 7.
41. Eight-celledstage, section at rightanglestolong axisofsuchstages asfigs.
7and8, showingprotoplasmicbridge.
42. Stageof8cells, section inplane a-hof fig. 10.
Platk VIII.
43. Eight-celled stage, section through a-h of fig. 12 showing a protoplasmic bridge.
44. Sixteen-celledstage,section inplane a-hoffig. 17.
45. Stageof16cells, sectionthroughplane a-hoffig. 16.
46. Stageof16cells, section inplane a-hoffig. 18.
47. Sixteen-celledstage, sectionthrough blastoderm likefig. 19.
48. High-arched 16-celled stage, section through l)lastoderm like fig. 22, with largesegmentationcavity.
49. Stageof32cells, sectionthroughablastodermlikefig. 23.
50. vStage of32cells, high-archedtyi)e, sectionisthrougha-h offig. 24.
51. Stageof 32 cells, thick-endedtypewith lai'gesegmentationcavityandthin central periblast.
52. Stageof32cells,sectionthroughahigh-arched blastodermsimilar tofig.25.
53. Thirty-two-celled stage. Nopenblast; two tiersof cells cutout of a solid massofprotoplasm.
54. Divided 32-to 64-celled stage. Noperiblast; basal protoplasm thick, with manyvacuoles, andhavingcell wallscuttingdownintoit.
NO.1431.
BREEDING HABITS AND EGG OF PIPEFISII-G VDGER. 499
Fig.55.
Plate IX.
Dividedthick-ended 32 to 64-celledtypeofblastoderm. ThespUtishere a narrowvertical cleft. Cellwalls arepushing intothe hasal layerwhich haslarge vacuoles.
56. Stage of64 cells. Section through a normal or gently arche.l type. One
cellnot yetfreefromcentral periblast.
^
57. Stageof64cells. TypewithflatsurfaceandaV)rupt edges. Inuclei arevery largeandinspiremestage.
.,, ^,
58 Samestage. High-archedtype. Cellsstillconnectedto periblast layer.
59^ Sectionthroughthick-endedblastodermof 64-celled stage. Nodistinctcen-
tralperiblast. . . . ,. ^
60. Stageof128 surfacecells. Normal typewith7 cells
m
processofformation frombasal layerofprotoplasm.61 Secondtypeof 128-celle<l stage. Central periblastladen with yolk.
62" High-arched typeof this stage. Mitotic spindles standatallanglestoeach other, andvacuoles aidincutting out thecellto right.
63 Fourthtypeof 128-celled stage. Cellsarebeingcutoutot the basal syncy- tium, the -Rand- isseparated fromthe outerperiblastbyasharpre-en-
trant angle.
Many
ofthedarklystained nuclei havebesidethemsolidly stained bodiesofunknown function.64
A
section through anotherthick-ende.l blastodermof this stage. There isnocentral periblast; cellshave beencut outofthesyncytium
65 Normaltvpeof 256-celled stage. Thenucleiallstain solidly,cellsare being cutofffrom theperiblast, the
"AW/"
isnucleated. This is the earlieststagewithnucleiin central periblast.
, , „ ,
66. Stageof 256 surfacecells, second type.
-Ramr
sharply marke.l off tromthe outerperiblast. ^u i ,coi
67. Same stage,third type, showingcells inprocess of formation in the
basal
svncytium. _
Plate X.
68. High-archedtypeofthis stage,withsolidlystained nuclei-periblastwholly freefrom cells.
.i i. f .k;^i, fl.r 69. Horizontal section through blastodermof same stage as thatot ^^hIch fig.
68 isavertical section.
70 Verticalsection through blastodermintermediatebetweenfigs.*^''>/indb7 7i: Stageof 512 surfacecells, normal type. Surface cells showanotable elon-
gation,some forming"bridges." . ,u^,„,^i^;
72. Hfgh-arched typeof this stage. The cells areof unequal sizes, the nuclei
stain solidly,theperiblastisnucleate.landinprocessofbuddingoff cells.
73 Same stage, flat-topped, abrupt-edged type. The "i^«»rf" is ot peculiar tinmass while onthe right awholespindleisshown.
74. 512-celled stage, fourth type. -Rand- and thick peribast nucleated.
Somecellswithmitoticfigures,but mostnucleistamsolidly.
75 Stageof1,024 cellsonsurface, normaltype. Outer cells flattening toform
"-
an epid;rmic stratumwhich is at places two-layered. Manynudeiand vacuoles are found in the periblast, out ot which a number of cells are 76. SamTstage; second tyge. The periblast is sunken in ^^e yolk,
^^
th«blastonu^res only sparingly fill the segmentation cavity thus enlarged.
Thenuclei areinthespiremestageanda-Declschicht ispreserit.
77. High-archedtypeof this stage. The thick periblast isvacuolatedand has a giant spindleatthe left
500 PROCEEDINGS OF THE NATIONAL MUSEUM.
vol.xxix.Fig.78. Section froaiablastodermlikefig.77,but withperiblastdeeplysunkinthe yolk, thus greatly enlarging thesegmentationcavity.
79. 1,024-blastomere stage, fourth type. A.^^DcckschicJd" is forming and the periblastisgivingrisetocells.
Plate XI.
80. Horizontalsectiontiiroughablastoderm of thesamestage asfig. 78. Epi- dermic stratumverydefiniteandinpart two-layered,
81. Late stage of segmentation. Section from a blastoderm intermediate betweenthe gentlyarchedandthethick-endedtypes. Blastomeresscat- teredinthelargesegmentationcavitycausedbythedown-sunkenperiblast.
82. Late segmentation stage, round-arched type. Epidermic layer present.
Manycellsrestingon periblast and probablyformed from it. The left outer i>eriblast shows twomultipolarspindles.
83. Sectionthroughlatelens-shapedblastula. The''DeckscJiidd"istwo-layered, and theperiblast, which hasno formingcells, isdeeply sunken.
84. Outline section of normal type late blastoderm. The cells have moved upward, formingacompactmass,thelowerlimit ofwhich ismarked xx,
and havingalarge subgerminalcavity. Giantnucleiin periblast. • 85. Lateblastoderm,second type,showingsamestructuresasfig.84. Periblast
much sunken.
86. Same stage, thick-ended type. Periblast is thin and multinucleate.
A
largebinucleate cellisshown.
87. Samestageand structures as above from a blastoderm like fig.83. Many
restingnuclei in periblast.
88. Normaltypeblastodermspreading over yolk preparatorytothebeginningof invagination.
89. Sectionfroma ])lastodermsimilar totheabovesavefora slightvariationin shape.
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. XXIX PL.V
Fig.10 Fig, 11
Segmentation of Pipefish Eggs.
For explanation of platesee page 497.
U. S. NATIONAL MUSEgM PROCEEDINGS, VOL. XXIX PL. VI
Fig, 13
fig. 19
fig. 22
Fig. 25
Fig.16 Fig.14
Fig.23 Fig. 24
Fig. 26 Fig.27
Segmentation of Pipefish Eggs.
Forexplanation of plateseepages 497,498.
r^
2U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. XXIX PL. VII
Fij.29
Segmentation of Pipefish Eggs.
For explanation of plate see page 498.
II
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. XXIX PL. VIII
fig.45 p
fle-51
fll.47
Segmentation of Pipefish Eggs.
For explanation of plateseepage498.
U.S. NATIONALMUSEUM PROCEEDINGS,VOL. XXIX PL. IX
Fij.65
flg.66i
Segmentation of Pipefish Eggs.
For explanation of plate see page 499.
Proc.N.M.vol.xxix—05 33
1
U.S. NATIONAL MUSEUM PROCEEDINGS, VOL. XXIX PL. X
rt.77
Fi|-78
Segmentation of Pipefish Eggs.
For explanation of plateseepages 499,500.
1
U.S. NATIONAL MUSEUM PROCEEDINGS, VOL. XXIX PL. XI
Segmentation of Pipefish Eggs.
For explanation of plateseepage 500.