S|)ontaneous Fission in Hydroids. 
By 
P. L. Kramp. 
(Communicated at the meeting of December lOth 1915.) 
With Pia le III. 
(j. J. Allman was the first observer of spontaneous fission in 
hydroids (Allman 1871). Some colonies of a Laomedea had 
been placed in a glas jar; some of the branches did not develope 
into hydranths, but prolonged themselves rapidly into long cylin- 
drical threads with an extremely fine chitinous cover. At some 
distance below the distal end the coenosarc narrowed, and a small 
sausage-shaped body was isolated and emitted into the water. This 
body attached itself to the wall of the jar and became a kind of 
stolon, from which a hydranth was developed by budding. A new 
colony was founded. 
In his monograph (1872) Allman quoted his original note on 
the matter, and added as a faet of special interest, that the colo¬ 
nies, in which the phenomenon was observed, did not possess gono- 
somes, and he expressed the opinion, that spontaneous fission does 
not oceur at the same time as the sexual individuals are devel¬ 
oped. 
Allman considered the spontaneous fission to be a specific 
peculiarity of the hydroid in which he had observed it, and he 
described this form as a new genus and new species, Schizocla- 
diiiin rainosiim. There can be no doubt but that it has been a 
species of Laomedea, probably of the subgenus Obelia. Allman 
himself remarks, that it bears a great likeness to L. dichotoma. 
His figures are, however, not sufficiently clear as to serve as base 
for a reliable Identification. 
Hincks (1872) observed a similar phenomenon in a colony 
of Laomedea neglecta. He presumed it to be a phenomenon of 
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