JOURNAL OF MICROSCOPICAL SCIENCE. 
DESCRIPTION OF PLATE II, 
‘Mlustrating Professor Allman’s paper on the Mode of Repro- 
duction by Spontaneous Fission in the Hydroida. 
Fig. 
1. Schizocladium ramosum, nat. size. 
2. A portion of a colony magnified. a, A fissiparous ramulus previous to 
the commencement of fission; 4, the ccenosarcal contents of the 
ramulus have extended themselves beyond its extremity, having in 
their elongation ruptured the chitinous perisare which lay over 
this part of the ramulus, while the commencement of fission shows 
itself in a constriction of the ccenosare at a little distance behind 
its free extremity ; c, the constriction has advanced so as to have 
now cut off a piece from the extremity of the ccenosare and the 
detached frustule has begun to slip out of the chitinous sheath ; 
d, the frustule has become a free zooid entirely disengaged from 
the sheath of the ramulus. 
3. The free fission-frustule more magnified. 
4. The frustule has become attached to the sides of the vessel and has 
excreted a membranous tube from which it has partially withdrawn 
itself, 
5. The frustule has began to emit a bud from its side. 
6. The bud has become elongated into a stem. 
7. The free extremity of the stem is becoming developed into a hydranth 
with its hydrotheca. 
8. The hydranth and hydrotheca are now fully developed, and the young 
trophosome has begun to complicate itself by the emission of a 
branch. 
