22 Echin. 
V. Echinoderma. 
[1906] 
DEVELOPMENT. 1015 
1. General principles. 
Vacant ; but see 1015, 8. 
2. General Accounts. 
a. General account of development of 
Echinoderma ; MacBride, 2, (601-621, 
figs.). 
/. Ditto, Crino idea ; Hamann (151 2— 
1537). 
3. Formation of gonads. 
/. Formation and growth of oocyte 
and yolk-nucleus, Antedon’, Chubb, 2. 
4. Oviposition, fertilisation, seg- 
mentation. 
Fertilisation, Arhacia ; Ariola. 
Attraction of ova for spermatozoa 
neither specific nor chemotropic ; Drago. 
Individuality of Ech. ova, those of 
same individual responding differently to 
stimuli ; Delage, 2. 
Sperm-ova and their segmentation, 
Ophiothrix ; MacBride, 1. 
Segmentation, Arhacia, Echinus, 
Strongylocentrotus ; Fischel, 2, (526). 
5. Larval stages. 
a. Various larvae in plankton ; Gough. 
Larvae in Plankton, North Sea ; Oon- 
seil internal, 1, 2 & 3. 
Plankton, Murman Sea; Derjugin, 
(104, 161). 
Bipinnaria and Pluteus ; Delap, 1 , (5). 
h. Young of Synapta , with contractile 
rosettes ; Becher, (508). 
Larvae of Elasipoda, probably Elpi- 
diinae, descr ; Herouard, 2, (9). 
c. Parthenogenetic Paracentrotus 
raised in 1 month to Echinoid with 2 
pedicellariae ; Delage, 2. 
Ech. blastulae and gastrulae always 
come to top of water, geotropism ; 
Lyon, 2. 
d. Bipinnaria of Luidia sarsi, 
growth of young to 95 mm. diam. ; 
Delap, 2, (15). 
Larva of Stellosphaera, 2 stages ; 
Koehler & Vaney, 1 & 2. 
e. Early stages, Ophiothrix, right 
hydrocoel; MacBride, 1. 
6. Organogeny. 
h. Development of spicules in 
Cucumariidae and Synapta ; Woodland, 
(figs., pis.). 
c. Symmetry, bilateral, first visible 
in Gastrula with mesenchyme, but fore- 
shadowed in stage with 2 precocious 
micromeres. In a half blastomere 
larva the median plane is at right 
angles to the original median plane, i.e. 
the primitive groove. Dispersing des- 
troys bilaterality ; Driesch, 1 and 2. 
Development of pedicellariae in 
Echinotkuridae ; Schurig, (306, fig.). 
d. Skin glands, Echinastcr, Cribrella ; 
Barthels. 
7. Post larval growth-stages. 
h. Growth-stages of Cucumaria, 
corresponding to Ocnus, Cucumaria, 
and Semperia ; Herouard, 2, (12). 
Increase of pigment and other changes 
in integument of spp. of Eolothuria 
with age and change of habitat ; 
Polara, 2. 
c. Development of Hemicidaris 
crenularis from 2 mm. to 35 mm. dia- 
meter ; Sdguin, 1 A 2. 
Characters of young Echini in general 
(211), Sterechinus horvidus, 8 mm. diam. 
(222) ; Doederlein, 2. 
d. Young of numerous Hawaian 
Ast., for list of genera see 1027, A, iv ; 
Fisher, 3. 
Young of Crossas'er alternatus ; 
Fisher, 4, (134). 
Young of Anasterias tenera descr. ; 
Koehler, 5, (17, pi.). 
/. Young of Dizyjocr. (1252), in- 
crease of basals with growth in Talarocr. 
(1262); Beede. 
