548 CKESSWELL SHEAKEK AND DOROTHY JORDAN LLOYD, 
(1) 3 c.c. N/10 butyric acid + 50 c.c. sea-water for 1'5 
minutes. 
(2) Wasli in two or three changes of sea- water and transfer 
to — 
(3) 10 c.c. sea-water -f 40 c.c. 1'13 M sucrose solution -f- 
1‘4 c.c. M/60 tanic acid for 6 minutes. 
(4) 1'5 c.c. N 10 ammonia is added to (3) for 1 hour. 
(5) Wash in three or four changes of sea-water and transfer 
to normal sea-water. 
Finally, there is always a sFight difference distinguishable 
between all parthenogenetic larvte as compared with normal 
sperm-fertilised ones. This is noticeable in length of arms,, 
pigmentation, and rate of growth. 
Bibliogeaphy. 
1. Allen, E. J., and Nelson. E. W. — “ On the Artificial Culture of 
Marine Plankton Organisms,” ‘ Journ. Mar. Biol. Assoc.,’ vol. 
vii, 1910, p. 421. 
2. Berkely, Lord, and Hartley. — “ The Osmotic Pressure of Sucrose 
and Dextrose," •Phil. Trans.,’ A. 1900, ccxcvi, p. 481. 
3. Delage, Y. — “ Etudes exiierimentales sur la Maturation Cj’toplas- 
mique et sur la ParthOiogOiese Artificielle chez les Echino- 
dermes,” ‘Arch, de Zool. Exper. et Gen.,’ 3 serie, tome 9, 1901, 
p. 285. 
4. “ La Parthenogeuese par I’Acide Carbonique obtenue chez les 
oeufs apres remission des Globules polaires,” ‘Arch, de Zool. 
Exper. et Gen.,’ 4 serie, tome 2, 1904, p. 43. 
5. “Les Vrais Facteurs de la Parthenogeuese Experimentale ;. 
elevage des larves parthenogenetiques juscpi’a la forme parfaite,” 
‘Arch, de Zool. Exper. et Geii.,’ 4 serie, tome 7, 1908, 445. 
6. Hindle, E.— “ A Cytological Study of Artificial Parthenogenesis in 
Strongylocentrotus purpuratus.” ‘ Archiv f. Entwickl. 
Mech.,’ vol. xxxi, 1910, p. 145. 
7. Loeb, Jacques. — ‘ Amer. Journ. Physiol.,’ hi, 1899. p. 135. 
8. ‘Amer. Journ. Physiol.,' iv, 1900, p. 178. 
9. ‘Amer. Jouni. Physiol.,’ hi, 1900, p. 434. 
10. ‘ U. Calif. Pul\ Physiol.’ ii. 1905, p. 83. 
