226 i iy d r o d ic t y o n eæ .
issuing from the interior of the membrane in which it Avas
contained, and Avhich, Avithout doubt, was open for the purpose
of its escape *; and after this separation it floated on the
water under the form o f a cylindrical cell. Soon it flattened
itself, and imderAvcnt an alteration, Avhich I Avovdd compare
to that Avhlch the beginning of fusion produces upon
metals; then it increased gradually in every direction, and,
the reticulations being cleared the one from the other, became
itself a ncAV netAvork, Avhlch one might distinguish
Avith the microscope. Soon the reticulations Avcre to be seen
Avith the unaided sight, and at last each cell (or division o f
the pentagon), Avas totally changed into a network entirely
like to that of Avhich it made part. All these transformations
took place in the space of a fcAV days, and at the end of tAvo
or three months the young reticulated productions had acquired
the full dimensions of which they Avere capable.........................
We have here then an example of reproduction more remarkable
perhaps than those heretofore observed.”
“ In c o n c l u s i o n , t h e r e i s b u t l i t t l e r o o m t o d o u b t t h a t i f t h e
s id e s o f t h e r e t i c u l a t i o n s o f t h e n e tA Vo rk o f t h e p r e c e d i n g
y e a r be t h e n e tA V o rk s o f t h i s y e a r , t h e s id e s o f t h e r e t i c u l a t i o n s
o f t h e p r e s e n t n e tA V o rk s Avill a l s o b e t h e n e tw o r k s o f t h e n e x t
y e a r , t h a t e a c h c e l l o r f ib r e o f t h e r e t i c u l a t i o n s i s i t s e l f t h e
n e tw o r k A vh ich s h a l l d e v e l o p e i t s e l f o n t h e s e c o n d y e a r , a n d
t h a t t h e f ib r i l la o f t h e p r in c i p a l f ib r e w i l l b e t h e n e tw o r k
A v h ich s h a l l d e v e l o p e i t s e l f o n t h e n e x t y e a r , a n d s o on u n t i l
i t p l e a s e t h e A u t h o r o f N a t u r e t o p u t a n e n d t o t h i s d e v e l
o p e m e n t b y d e s t r o y i n g t h e s p e c i e s A vhich p r e s e n t s i t . ”
* Areschoug, Avho has published an excellent paper in Schlechtendal’s
“ LinnaBa,” for 1842, on the mode of growth of Hydrodictyon utriculatum,
states that he has never been able to detect in this plant the enclosing
tube. Dr. Areschoug has made the interesting discovery of the exact
mode of formation of the minute network, viz., by the union of the
numerous spores while in the parent cell, previously to which they are
observed to be in lively motion; the parent cell itself is absorbed, and
thus the neAV plant is eliminated according to Areschoug.
221
F am . XII. SCYTONEMEÆ.
Char. Algæ fo r the most p a rt branched, rigid, or flaccid.
Cells globular or compressed. Colour either a dark olive
or a vivid ceruginous green.
The Algæ described in this family form two very distinct
sections ; the first section embracing those species which arc
characterized for the most part by a rigid cartilaginous habit,
globular cells, a black or olivaceous colour, being lustreless
in drying, and the second division including species Avhich are
not of a rigid habit, but whose filaments are flaccid, cells usually
cylindrical, and colour a vivid green. The species of this
last section Kiitzing makes the type of his order Paraspermeoe,
an order characterized hy its lateral sporules, and including
Lyngbyaceæ and Calothriceoe, families which folloAV in Ids
arrangement the Scytonemece.
Section i. S t i g o n e m e j e .
22. STIGONEMAAy.
Char. Filaments lifted, branched, o f irregular diameter, cartilaginous.
Cells moniliform, arranged in transverse lines.
Derivation. From ariymv, dotted, and vyga, a thread.
There is scarcely any necessity for this genus: the species
described in it Avould form a natural section of the genus
Hassallia.
1. S t ig o n em a a t r o v ir e n s Ag.
Pk LX V I. Fig. 1.
Char. Filaments tufted, coarse. Branches slightly divided,
subacute. Rings mostly formed o f three cells.
Q 2