Actinoida 
Actinoida (ak-ti-noi'da), H. pi. [NL. : see acti- 
nvid.] Same as Actlnosoa. 
actinolite (ak-tiu'o-lit), . [< Gr. o/trt'f (OKTW-), 
ray. + /.('(tof, stone.] A radiated mineral, called 
by Werner strahlstein (ray-stone), consisting of 
silicates of calcium, magnesium, and iron, it is 
a variety of amphibole or hornblende, of a green color, mill 
having a columnar to fibrous structure. Also called acti- 
iwte. Actinolite schist, a metamorphic rock consisting 
principally of actinolito, with an admixtureof mica, quartz, 
or feldspar ; its texture is slaty and foliated. 
actinolitic (ak"ti-]io-lit'ik), a. Like, pertaining 
to, or consisting of actinolite. 
actinology (ak-ti-nol'o-ji), . [< Gr. auric (<- 
TIV-), ray, + -/loj/a, < l&ffu, speak : see -ology.] 
That branch of science which investigates the 
chemical action of light. 
actinomere (ak-tin'o-mer), n. [< Gr. d/m'f (d/c- 
TIV-), ray, + fiepof, a part, < [ici/ieaOat (^/ */< E P)> di- 
vide.] One of the radially symmetrical parti- 
tions or divisions of a sea-anemone, coral-polyp, 
or other actinozoan. 
actinomeric (ak"ti-no-mer'ik), a. Relating to 
an actinomere ; having actinomeres ; being di- 
vided into radiated parts. 
actinometer (ak-ti-nom'e-t*r), . [<Gr. d/cr/f 
(dxTiv-), ray, + pcrpov, measure.] An instru- 
ment for measuring the intensity of the sun's 
heat-rays. 
actinometric (ak*ti-n6-met'rik), a. Of or 
belonging to the actinometer, or to actinom- 
etry. 
actinometrical (akti-no-met'ri-kal), a. Same 
as actinometric. 
actinometry (ak-ti-nom'e-tri), w. [As aetinome- 
ter + -y.~\ The measurement of the intensity 
of solar radiation. 
Actinomma (ak-ti-uom'a), n. [NL., < Gr. auric, 
(O.KTIV-), ray, + ii/j/ia, eye.] A notable jpnus of 
radiolarians, established by Haeckel m 1860. 
See extract. 
As the lateral processes [of the rays of some radiolari- 
ans] . . . become more largely developed, a continuous cir- 
cumferential skeleton is formed, which encloses the whole 
organism, as in Actinmtima, in which there are sometimes 
three or more concentric shells. Stand. A'at. Hi#t., 1. 9. 
Actinomonadidae (ak'ti-uo-mo-nad'i-de), n. pi. 
[NL., < Actinomonas (-ad-) + -i'rfo,'.] A family 
of oval or spheroidal animalcules, fixed or 
freely motile. They are entirely naked, possess neither 
a hardened test nor a central capsule, and have flue ray- 
like pseudopodia projecting from all points of the surface, 
supplemented at one point by a long vihratile tlagellum. 
Actinomonas (ak"ti-no-mon'as), H. [NL., < Gr. 
dicT/f (OKTIV-), ray, + povds, a unit: see monad.} 
The typical genus of infusorians of the family 
Actinomonadida: 
actinomorphic (ak'ti-no-mor'fik), a. Same as 
actinomorphous. 
actinomorphous (ak"ti-n6-mor'fus), a. [<Gr. 
d/crif (iiKTiv-), ray, + /#y)0;/, form.] Kay-shaped: 
in lot., applied to flowers which may be divided 
vertically into similar halves through two or 
more planes : synonymous with polyttym metri- 
cal. Sachs. 
actinomyces (ak'ti-no-mi'sez), .; pi. aetinomy- 
cetes (-ml-se'tez). [NL., < Gr. dxr/f (d/rrro-), 
ray, + [ivw/f (pi. jimr/res), a musliroom, an ex- 
crescence.] The ray-fungus: so called from 
the rosettes of club-shaped structures in which 
it presents itself. The disease actinomycosis 
is caused by the presence of this fungus. 
actinomycetic (ak'ti-no-mi-set'ik), a. Per- 
taining to or caused by actinomycetes : as, an 
aetinomycetic tumor. 
actinomycosis (ak"ti-n6-ml-k6'sis), n. [NL., < 
actinomyces + -osis.} A progressive inflamma- 
tory affection caused by the presence of acti- 
uomycetes, occurring in cattle and swine, and 
sometimes in man. It is most frequently found in 
the jawa of cattle, but may invade other parts. It is com- 
municated by contact with a wound or an abrasion. Also 
called lumpy-jaw. 
actinophone (ak-tin'o-phon), . [<Gr. d/m'f 
(O.KTLV-), ray, + <jxjvi/, sound.] An apparatus for 
the production of sound by actinic rays. A. G. 
Bell. See radiophone. 
actinophonic (ak-tin-o-fon'ik), a. Pertaining 
to the actinophone, of to sounds produced by 
actinic rays. 
actinophpre (ak-tin'o-for), n. [< Gr. anTtvo^poc,, 
ray-bearing: see actinopitorous.] One of the 
peripheral skeletal elements which directly af- 
ford support to the true fin-rays of Lyrifini. 
that is, typical fishes and selachians. 
The actinophoren of the paired flns may be distinguished 
from those of the unpaired fins by calling the latter the 
median actinophores. J. A. Ryder. 
actinophorous (ak-ti-uof o-rus), a. [< Gr. im- 
ray-bearing, < a/rrij- (d/cr<*-), ray, + 
60 
-<t>6pof, < 0tpeiv = E. hear 1 .] Having ray-like 
spines. 
actinophryan (ak-ti-nof'ri-an), a. [< Ai'lhio- 
plirys.] Of or pertaining to Actinophrys. 
The am<ban, like the actinophryan type, shows itself in 
the testaceous as well as in the naked form. 
W. B. Carpenter, Micros., 407. 
Actinpphryidae(ak''ti-ii6-fri'i-de), n.pl. [NL., 
< Actino/tlirys + -idte.'\ A family of endoplastic 
rhizppods, typified by the genus Actinophrys 
(which see), referred to the order Heliozoa or 
constituting an order Phkeophora (Cams), and 
containing organisms known as heliozoans or 
sun-animalcules. Other genera than Aetiim- 
phrys placed in this family are Cttiophrys and 
Actinosphcerium (which see). 
Actinpphryina (ak*ti-n6-fri-i'na), n. pi. [NL., 
< Aetinoplirys + -ina.} A group of rhizopods, 
taking name from the genus Actinophrys, con- 
taining heliozoans or sun-animalcules. See Ac- 
tiiiophryida. 
Actinophrys (ak-ti-nof'ris), . [NL., < Gr. d/cr/f 
(OKTIV-), ray, + bifipitc, = E. brow.} A genus of 
protozoans, belonging to a division of the class 
Rhizopoda known as Heliozoa, and the leading 
genus of a family Actinophryida: Actinophrys >ol, 
a typical species, is the well-known sun-animalcule of 
microscopists. 
Most species of the genus Actinophryu, or "sun-animal- 
cule," which is common in ponds, are simply free-swim- 
ming myxopods with stimsh pseudopodia, which radiate 
from all sides of the globular body. 
Huxley, Anat. Invert., p. 82. 
actinopteran (ak-ti-nop'te-ran), n. One of the 
Artiimjiteri ; an actinopterous fish. 
Actinopteri (ak-ti-nop'te-ri), n. pi. [NL., pi. 
of actinopterus : see actinopterous.} In Cope's 
system of classification, a subclass of fishes 
embracing all the teleosts, most of the osseous 
ganoids, and the sturgeons. The technical charac- 
ters of the group are opercular hones well developed ou a 
separate and complex suspeusorium, a double ceratohyal, 
no pelvic elements, primary radii of the fore limb parallel 
with basilar elements and entering into the articulation 
with the scapular arch, and basilar elements reduced to a 
inetapterygium and very rarely a me&opterygiuiu. 
actinopterous (ak-ti-nop'te-rus), a. [< NL. ac- 
tinopterus, < Gr. auric, (OKTIV-), ray, + irrepov, 
wing.] Having the characters of or pertain- 
ing to the Actinopteri. 
actinosoma (ak"ti-n6-s6'm&), n.i pi. actinoso- 
matn (-ma-ta). [< Gr. auric, (CIKTIV-), ray, + aufia, 
body.] The entire body of any actiuozoan, 
whether simple, as in the sea-anemones, or com- 
posed of several zooids, as in most corals. 
Actinosphserium (ak*ti-n6-sfe'ri-um), n. [NL., 
< Gr. oKT/f (d/criD-), ray, + afyalpu, sphere.] 1. A 
genus of rhizopods, or endoplastic protozoans, 
n 
Sun-animalcule {Actinosphariitm eichhorni}, magnified. 
1. The whole animal, with c, c, contractile vacuoles. II. Portion of 
periphery more magnified, with a, four stiff pseudopodia. and n, 
lour nuclei or endoplasts. III. A young actinosphferium. 
having a number of nuclei or endoplasts in the 
central parts of the protoplasm, and numerous 
stiff radiating pseudopodia. 
Neither conjugation nor fission has been observed 
among ordinary Radiolaria, but both these processes take 
place in Actinogphcerium. Huxley, Anat. Invert., p. 85. 
2. [/. c.] A member of this genus, 
actinost (ak'ti-nost), n. [< Gr. d/m'f (attnv-), 
ray, + bareov, a bone.] In ichtli., one of the 
bones which in true fishes immediately support 
the rays of the pectoral and ventral fins. They 
are generally, in the pectorals, four in number, but some- 
times, as in some pediculates, are reduced to two, and 
sometimes, as in ganoids, increased to more than four ; 
they are rarely atrophied. Gill. 
action 
actinostome (ak-tin'o-stom), w. [< Gr. auric, 
(uKrtv-), ray, + aro/ta, mouth.] The oral orifice 
of an actinozoan. 
The ingrowth of the rim of the blastoport) in Actinozoa 
to form an actimixlome is therefore due to a fusion be 
tweeu the primitive stomodeum and the blastopore. 
llmitt. Proc. Host. .Hoc. Nat. Hist. (1885), p. 107. 
actinote (ak'ti-not), H. [< Gr. d/cm>urof, fur- 
nished with rays, < auric, (tutrtv-), ray.] Same as 
aetinoUte. 
actinotrichium (ak'ti-no-trik'i-um), n. ; pi. ac- 
tinotrichia (-a). [NL. (J. A. Ryder, 1885), < Gr. 
d/cr/f (d/crw-),"ray, + Bpif (rpix-), a hair.] One 
of the homogeneous hair-like fibers which rep- 
resent the rays in the fin-folds of the embryos 
of fishes, and which subsequently fuse to form 
the membranous basis of the permanent rays 
of the adult fish. 
Actinotrocha (ak-ti-not'ro-ka), n. [NL., < Gr. 
d/cr/f (OKTIV-), ray, + rpojrjij & wheel, ring.] An 
embryonic form of a gephyrean worm of the 
genus Phoronis (which see), which was mistaken 
for a distinct animal and named Actinotrocha 
branchiata. 
Actinozoa (ak"ti-n6-zd'a), n.pl [NL.,<Gr. d/cr/f 
(axriv-), ray, + foi\ an animal : see zoim.} A 
class of (telenterata; 
radiated, marine zo- 
ophytes, embracing /I 
the sea-anemones, / 
corals, sea-pens, / 
etc., in which the / 
mouth is furnished I 
with hollow retract- I ,? 
ile tentacles, simple I j] 
in one subclass (Zo- I , v 
antharia) or fringed \\ f 
in the other (Alcyo- ^^ 
naria). The digestive Vertical Section of an Actinozoall 
cavity is Separated from (a sea-anemone. Actinia holsatical. 
the body-wall by an in- showing type of structure of Actincatoa. 
a, moutn, oral aperture ; b, gastric 
cavity; c, axial cavity, common to * and 
to rf, an intermesenteric chamber in the 
tervening perivisceral 
space, which is radially 
divided into several com- perivisceral or somatic cavity' V and ~d 
parttuents by partitions together being the enterocoele ; f, free 
ailed mesenteries, ill ""ckened margin of a mesentery, /. 
which thf rmraOnsUv* containing nematocysts ; f. reproduc- 
e rive organ; h, one of the circlet of 
organs are Situated. Hie tentacles around the mouth. 
great majority are com- 
pound, living in a polypidom; some adhere to rocks, etc., 
and some are free. The rayed tentacles about the mouth 
present in some genera, as Actinia, no remote resem- 
blance to some of the finest composite flowers. Reproduc- 
tion is effected by eggs thrown out at the mouth, by gem* 
mules or buds developed on the base of their disk, and by 
division, each separated part becoming a complete ani- 
mal. They present the phenomenon known as metagen- 
esis or alternation of generation. When reproduced by or- 
dinary generation, the egg develops into a free locomotive 
planula with vibratile cilia. The sexes are either united 
or distinct. The Actinozoa and Hydrozoa constitute the 
subkingdom Ccelenterata. Also called Actinoida. .See Hy- 
drozoa. 
actinozoal (ak*ti-no-z6'al), a. Relating to the 
Actinozoa. 
actinozoan (ak"ti-n6-z6'an), n. One of the Ac- 
tinozoa ; any member of that class. 
actinozodn (ak"ti-n6-z6'on), n. [NL., sing, of 
Actinozoa.} An actinozoan. 
actinula (ak-tin'u-la), .; pi. actinulte (-le). 
[NL., dim. of Gr. d/cr/f (OKTIV-), ray.] A name 
given by Allman to the larval condition of 
Hydrophora (Hydrozoa), appearing when the 
ciliated locomotive planula or embryo has be- 
come fixed by its aboral end, and has passed 
into the elongated gastrula-stage by the forma- 
tion of the mouth with its circlet of tentacles. 
See planula. 
In most Discophora, the embryo becomes a fixed actin- 
ula (the so-called Hydra tuba, or Scyphistoma). 
Huxley, Anat. Invert., p. 133. 
action (ak'shon), n. [< ME. accion, -aim, < OF. 
action = Sp. accion = Pg. ace. So = It. azione, < L. 
actio(n-), < agere, do, a,ct: see act, n.} 1. The 
process or state of acting or of being active, as 
opposed to rest; change of which the cause lies 
within the subject ; activity ; active exertion ; 
energy manifested in outward acts, as con- 
trasted with contemplation, speculation, speak- 
ing, or writing: as, a man of action. [In this 
sense not used in the plural.] 
The basis of Action, as distinguished from motion, or 
movement, is the existence of desire residing in the ani- 
mate organism. L. F. Ward, Dynam. Sociol., II. 90. 
2. An event considered as predicated of its 
cause ; an act, usually in a complex or an in- 
clusive sense ; that which is done about or in 
relation to anything; a specific performance, 
proceeding, or course of conduct : as, a good 
or a bad action; actions speak louder than 
words ; the action of a deliberative body. 
The Lord is u Ood of knowledge, and by him activnt 
an: weighed. 1 Sam. ii. 3. 
