Marcu 14, 1884.] 
The reproduction of Clathrulina elegans. 
In Science, iii. 55, is published a réswmé of Miss S. 
G. Foulke’s remarks before the Philadelphia academy 
of natural sciences in reference to the reproductive 
methods of Clathrulina elegans; her statements being 
app trently confined chiefly to a process by quadruple 
suvdivision of the body into uniflagellate organisms 
as observed by herself, with allusion to three addi- 
tional processes as observed by others. In August, 
188i, the writer repeatedly witnessed two forms of 
reproduction with this rhizopod, in some respects 
quite different from what was observed or mentioned 
by Miss Foulke. 
The body of Clathrulina in no instance withdrew 
its rays before subdivision, but underwent transverse 
binary fission; each part, even after complete separa- 
tion, retaining its pseudopodal rays fully extended. 
Soon after dividing, however, one part became per- 
fectly smooth, having possessed up to this point a 
conspicuous pulsating vacuole, which now curiously 
contracted, and did not re-appear. The remaining 
half of the original body underwent no change ex- 
cept that caused by the protrusion of rays from the 
freshly divided surface. 
The recently separated portion then slowly passed 
out of the capsule, forming, just before its escape, two 
vibratile flagella of unequal length. Its movements 
began immediately, being only moderately active, and 
continuing for less than two minutes, when it sud- 
denly lifted itself upon the flagella-bearing end, and 
instantaneously collapsed into a shapeless mass stud- 
ded with short blunt pseudopodia, which almost as 
quickly became filiform; and the zooid was an Actino- 
phrys-like creature, with two flagella trembling at its 
front. The latter were soon lost among the rays, and 
the animal at once began to form the pedicle by a 
slow extrusion of the body-sarcode. The whole pro- 
cess consumed about three hours. 
From the same gathering I was also fortunate 
enough to learn how Clathrulina produces the colo- 
nies occasionally met with. The process, up to the 
escape of the biflagellate zooid, even with the strange 
conduct of the contractile vesicle, was as just de- 
scribed. The longer of the flagella, however, termi- 
nated in a conspicuous bulb-like enlargement, which 
remained within, but was not attached to, the parent- 
shell. The vibrations of the short lash gave the zooid 
a rapid rotatory and oscillating movement, the anchor- 
ing bulb slipping freely from side to side of the open- 
ing in the lattice. Motion continued for perhaps five 
minutes. The obovate body then became rounded, 
the smooth surface roughened by irregular protrusions 
extending into filiform rays, until another flagellate 
Actinophrys-like creature appeared, loosely anchored 
to a Clathrulina lattice. It remained motionless on 
the extremity of the apparently rigid bulb-bearing 
lash, which I supposed would become the pedicle; 
but in a few moments an unusually thick pseudo- 
podium was extruded, and attached by an expanded 
base to the capsule. On this the Actinophrys, with 
all its rays extended, was slowly lifted to the required 
distance above the parent; while the anchoring fla- 
Sellum became more and more attenuated, the bulb 
less and less noticeable, until both finally disap- 
peared. 
It seems, then, that Clathrulina elegans has six re- 
productive methods, — “‘ by self-division, by the in- 
stantaneous throwing-off of a small mass of sarcode, 
by the formation and liberation of minute germs,”’ by 
the quadruple subdivision of the body into uniflagel- 
late organisms, by the separation from the body of 
a free-swimming Heteromita-like zooid for the dis- 
SCIENCE. 
303 
semination of the species, and by a similar body-fission 
whose resulting biflagellate organism is anchored to 
the parent-capsule for the formation of a colony. 
Dr. ALFRED C. STOKES. 
Trenton, N. J. 
Formation of anchor-ice. 
On the 17th of January, this year, I had occasion 
to cross the River St. Lawrence in one of the small 
Indian ferryboats which ply between the Indian 
village of Caughnawaga, on the south shore, and 
Lachine, on the Island of Montreal. The current 
of the river at this point flows at the rate of four or 
five miles an hour, I think, and never freezes over. 
The day was quite stormy, the thermometer indi- 
cated about 12° or 15° F.; and the river was pretty 
thickly covered with cakes and masses of porous or 
very snowy ice. But the most peculiar phenomenon 
was the sudden and almost incessant rising of dark, 
muddy ice from the bottom of the river. The for- 
mation of this ice so far below the surface of the 
water is supposed to take place in very cold weather, 
when large masses of snow, descending the river, 
become saturated with water, and are carried by the 
current to the bottom, where they stick to the rocks 
and stones, clinging more firmly and becoming more 
compact as long as cold weather continues. At least, 
this is the theory that the Indians advanced. The 
ice may be seen six or eight feet under water, and 
often accumulates until it forms miniature islands. 
When it rises, it often lifts considerable quantities of 
small stones and gravel to the surface. 
Another peculiar circumstance is, that this rising 
of the ice from the bed of the river always occurs 
a day or two before the approach of mild weather; 
and the Indians regard this phenomenon as an in- 
fallible presage of milder weather within forty-eight 
hours. The cause is most likely atmospheric, but I 
record the observation with the hope that it may be 
a hint to some one willing to make a further study of 
the subject. 
Jie Gawd 
Chateauguay Basin, P. Q., Canada. 
Manayunkia speciosa. 
In this worm, described and figured by Leidy 
(Proc. acad. nat. sc. Philad., 1883), the tentacular 
crown, or branchial organ, is the feature of special 
interest. i 
According to Leidy, the tentacles present in an 
adult are eighteen in number, besides two larger and 
longer tentacles situated dorsally, midway between 
the two lophophores. These larger tentacles are con- 
spicuous by their bright green color, and are, in fact, 
external continuations of the blood-vessels extending 
lengthwise throughout the body. In shape these ten- 
tacles taper from base to apex, are convex on the 
outside, but concave on that side facing the centre of 
the tentacular crown; so that a transverse section 
would present the shape of a crescent. The two lon- 
gitudinal edges thus formed are fringed with cilia. 
When closely watched, the green tentacles are seen 
to pulsate with a rhythmical motion, contracting and 
expanding laterally. The pulsation takes place in 
each tentacle alternately. At the moment of con- 
traction the tentacle turns slightly on its axis out- 
wards, and towards the end of the lophophore on that 
side, at the same time giving a backward jerk, return- 
ing to its former position at the moment of expan- 
sion. By force of the contraction the green blood 
filling the tentacles is forced downwards, out of the 
tentacle, and flows along the blood-vessel on that 
