218 
The phenomenon here described seems to me to have a con- 
siderable biological interest, especially the question of the causes, 
a question which might probably be solved by means of experim- 
ents. — Starvation-experiments with certain species of athecate 
hydroids have been carried out by Will (1913). His paper about 
the matter contains some interesting observations but it is extremely 
speculatory. Phenomenons like the fission here described were not 
observed. — If I get an opportunity I will try to carry out a series 
of experiments respecting this matter, and if the present pages 
might direct the attention of other zoologists towards the matter, 
1 think it would be possible to reach a satisfactory explanation of 
an interesting example of adjustment in the nature. 
List of litterature. 
1871. Allman, G. J. — On a mode of reproduction by spontaneous fission 
in the Hydroida. — Quarterly Journ. of microscop. Science. 
New Ser. Vol. XI. — London 1871. pp. 18- 21. PI. II. 
1872. — A Monograph on the Gymnoblastic or Tubularian Hydroids 
1904. Billard, A. — Contribution å l’étude des Hydroides (multiplication, 
régénération, greffes, variation). — Annales des Sciences 
naturelles. Zool. Sér. 8. Tome XX. Paris 1904. pp. 1—252. 
PI. I—IV. 
1911. — Note sur un nouveau cas de scissiparité chez les Hydroides. 
— Buli. Mus. d’hist. naturelle. 
1897. Browne, E. T. — On keeping Medusæ alive in Aquarium. — Journ. 
Marine Biol. Ass. Vol. V. 1897—99. pp. 176—180. 
1905. Hallez, P. — Rhéotropisme de quelques Hydroides monosiphonés 
et des Bugula. — Comptes Rendus des Séances de f Acad. 
des Sciences. — Tome 141. Paris 1905. pp. 840—843 
1872. Hincks, Th. — Contributions to the History of the Hydroida. — 
Ann. Mag. Nat. Hist. Ser. 4, Vol. X. — London 1872. p. 385, 
PI. XX (III. Reproduction bv Fission in Campanularia neg- 
lecta, pp. 390—391, PI. XX, fig. 4). 
1913. Joseph, H. — Zur Frage der Langsteilung beim Siisswasserpolypen. 
Zoologischer Anzeiger. Bd. 43. pp. 74—78. 
1878. Mereschkowsky, C. — Studies on the Hydroida. — Ann. Mag. 
Nat. Hist. Ser. 5, Vol. 1. London 1878. — pp. 239 — 256. PI. 
XIII, XIV, XV. 
