protosiphon 
protosiphon (]>r6-to-si'fon), n. [< Or. irpirrof, 
!ir--t,+ K..V//I/NIH.] The representative or origin 
of the siphuncle in the protooonch of ammoni- 
iMi.l cephalopods. 
protosomlte (prd-to-so'mit), . [< Gr. -apuroq. 
first, + E. somite.] One of the primitive or 
rudimentary somites or segments of an embry- 
onic worm or arthropod. 
Generally, the development of the protomnitex, as these 
segment* might lie called, does not occur (In annelids] un- 
til some time after the embryo has been hatched. 
Huxley, Anat. Invert, p. 243. 
protosomitic (pro'to-so-mit'ik), a. [<protoso- 
nuli' + -ic.] Primitively segmented; oforper- 
t Dining to a protosomite. 
protospasm (pro'to-spazm), n. [< Or. trpurof, 
first, -r oiraa/tof, spasm : see spasm.] See Jaclc- 
siiiiiitn epilepsy, under Jacksonian. 
protospermatoblast (pro-to-sper'ma-to-blast), 
. [< Gr. jr/xjrof, first, + E. xpermaiobiast.] A 
cellular blastema in which spermatozoa origi- 
nate. See spermatobla.it. 
The spermatozoa of the decapods studied by him [Saba- 
tier | arise in large cells, the protospertnatoblasts, and are 
homologous with the epithelial cells of the Graaflan fol- 
licle. Micros. Sci., N. S., No. exit, XXX. 111. 251. 
Protospongia (pro-to-spon'ji-S), n. [NL. 
(Salter), < Gr. irpurof, first, + aitoyyia, a sponge.] 
A genus of lyssacine hexactinellidan sponges, 
including the oldest known forms of fossil 
sponge, from the Menevian beds of the Lower 
Cambrian of Wales, as P.fenestrata. 
protospongian (pro-to-spon'ji-an), a. Primi- 
tive, as a stage in the evolution of sponges or 
in the development of a sponge. Haeckel. 
We have not been able to separate the Protospongian 
stage of Haeckel from the ascula, and think it should be 
merged In the latter. 
Hyatt, Proc. Bost. Soc. Nat Hist, XXIII. 86. 
protospore (pro'to-spdr), w. [< Gr. Tryxirof, first, 
+ o-Topor, seed.] In bot., one of the primary 
or apparent spores of certain fungi, corre- 
sponding to the prothallus of the higher cryp- 
togams. 
Protostapedifera (pro-to-stap-e-dif'e-ra), n. pi. 
[NL., < Gr. ff/xjrof, first, + NL. Htapedifera, 
q. v.] A hypothetical form from which the Sta- 
pedifera are supposed to have originated. See 
Stapeilifera. Tliacher, 1877. 
Protostigrna (pro-to-stig'mji), n. pi. [NL. (Les- 
quereux, 1877), < Gr. -irpurof, first, + oriy/ia, a 
spot, mark.] A name provisionally given to 
certain doubtful plant remains, consisting of 
fragments of stems found in rocks of the Hud- 
son River (Cincinnati) group, near Cincinnati, 
and considered by the author of the name to 
be related to fUgillaria and other types of vege- 
tation of the Devonian and Carboniferous. The 
specimens found are very obscure, and are referred by 
some paleobotanista to the sponges or other low forms 
of marine life. 
protostoma (pro-tos'to-mil), . ; pi. protosto- 
mata (pro-tos-to'ma-tii). [NL., < Gr. Tr/wirof, 
first, + (iroua, mouth. 1 The archaeostoma or 
primitive mouth-opening of a gastrula, by 
which the protogaster or cavity of the archen- 
teron communicates with the exterior. It is the 
original orlttce of that Invaginatlon whereby a blastula is 
converted into a gastrula, and is mouth and anus in one. 
In some kinds of gastruke the protostoma is also called 
aniiK of HwKoiii in others, a blastvlapare. Haeckel, Evol. 
of Man (trans.), I. 194. 
Protosymphyla(pr6't6-siin-fi'lii), n.pl. [NL., 
< Gr. >r^roc, first, + NL. fiymphyla, q. v.] A 
term applied by Erich Haase to a hypothetical 
group, from which he supposed the orders $ym- 
pliyla, Thysanura, and Chilopodu to have been 
derived by evolution: its existence in nature 
is disputed or denied. 
protosymphylar Cpro'to-sim-fl'ljtr), a. [< Pro- 
tosymphyla + -ar.] Of or pertaining to the 
Protosympliyla. 
Protosyngnatha (pro-to-sing'na-thS), n. pi. 
[NL., < (Jr. nyxji-oc, first, + <rii>, alontf with, + 
yv6Bof, jaw.] A group of fossil mynapods of 
Carboniferous age, represented by the genus 
Paltfocampa, resembling the extant chilopods 
in having but one pair of legs to each segment 
of the body. Also called Protwtygnatlta. 
protosyngnathous (pro-to-sing'na-tbus), . 
[< ProtoxyngnatlM + -MIM.J Of or pertaining 
to the I'rutogyngnatha, or having their charac- 
ters. 
prototergite (pr6-to-ter'jit), H. [< Gr. vptiTOf, 
first, + L. tergum, back.] In entom., the first 
dorsal segment of the abdomen. 
protothallus (pro-to-thal'us), n.; pi. protothal- 
li (-i). [NL., < Or.' irparof, first, + 0a/Mf, a 
young shoot.] In bot. : (a) Same as protlml- 
luini. (b) Same as Iti/potliallus. 
4800 
protothere (pro'to-ther), n. A mammal of tho 
group Prototheria; any prototherian. 
Prototheria (pro-to-the'ri-a), . pi. [NL., < 
Gr. wparof, first, + Orm, a wild beast.] 1. A 
name proposed by Gill in 1872 for one of the 
major groups of the Mammalia, consisting of 
the Monotremata alone, as distinguished from 
the Kutheria: coextensive with ornitlitMli-l/ihia. 
2. Those unknown primitive mammals which 
are the hypothetical ancestors of the mono- 
tremes: synonymous with Promammalia. 
It will be convenient to have a distinct name. Protothe- 
ria, for the group which includes the at present hypo- 
thetical embodiments of that lowest stage of mammalian 
type of which the existing monotremes are the only known 
representatives. Huxley, Proc. Zool. Soc., 1880, p. 653. 
prototherian (pro-to-the'ri-an), a. and n. [< 
Prototheria + -an.] ' I. a. Primitively mamma- 
lian ; primeval or ancestral, as a mammal ; of 
or pertaining to the Prototheria in either sense. 
n. . A member of the Prototheria, hypo- 
thetical or actual. 
protothoraz (pro-to-tho'raks), n. [< Gr. irpuror, 
first, + Oupa!-, thorax.] Same as prothorax. 
Prototracheata (pro-to-tra-ke-a'ta), . pi. 
[NL., < Gr. jrpwroc, first, + rpaxeia, trachea, 
+ -ate 2 .] Same as Protracheata. 
prototypal (pro'to-tl-pal), a. [< prototyp-e + 
-al.] Pertaining to a prototype; forming or 
constituting a prototype or primitive form; 
archetypical. Also prototypical. 
Survivors of that prototypal flora to which I have already 
referred. Dawnon, OeoL Hist of Plant*, p. 24. 
prototype (pro'to-tlp), n. [< P. prototype = 
Sp. It. prototipo = Pg. prototype, a prototype; 
LL. prototypus, original, primitive ; < Gr. irpo- 
ToTvmif, in the first form, original, neut. npuru- 
TVTTOV, a first or primitive form, < Trpuror, first, -f- 
rrirof, impression, model, type: see type.] A 
primitive form; an original or model after 
which anything is formed; the pattern of any- 
thing to be engraved, cast, etc.; an exemplar; 
an archetype ; especially, in metrology, an ori- 
ginal standard, to which others must conform, 
and which, though it may be imitated from 
something else, is not required to conform to 
anything else, but itself serves as the ultimate 
definition of a unit. Thus, the mttre des archieet is 
a prototype, and so Is the new international meter at Bre- 
teuil, although the latter is imitated from the former. 
But the mitre du conservatoire and the meters distributed 
by the International Bureau are not prototypes, since 
they have no authority except from the evidence that they 
conform to other measures. 
In many respects [he] deserves to be enniched, as a pro- 
totype for all writers, of voluminous works at least. 
Sterne, Tristram Shandy, ill. 38. 
The square or circular altar, or place of worship, may 
easily be considered as the prototype of the Sikra surround- 
ed by cells of the Jains. 
J. Fergunmt, Hist. Indian Arch., p. 208. 
prototypembryo (pr6"to-tip-em'bri-o), H. [< 
prototype + embryo.] A later stage of the em- 
bryo, which exhibits the essential characters 
of the division of animals to which it belongs. 
Thus, the veliger of a mollusk, the nauplius of a crusta- 
cean, and the notochordal stage of a vertebrate are re- 
spectively prototypembryoi of the MolltiKa, Cruntacea, and 
rertebrata. Hyatt. (Rare.] 
prototypembryonic (pro'to-tip-eni-bri-on'ik), 
a. [<. prototiji>cmbrijo(n-} + -ic.] Having the 
character of a prototypembryo. [Kare.] 
prototypical (pro -to -tip' i- 
kal), a. [<. prototype + -ic-al.] 
Same as prototypal. 
Their [the Maruts'] coming to the 
fight must be taken as prototypical 
of the coming of the Greek heroes to 
the great fields of battle. 
Keary, Prim. Belief, p. 152. 
protova, 11. Plural of proto- 
ruiii. 
protovertebra (pro-to-ver'- 
te-brft), n. ; pi. protovertebrx 
(-bre)'. [NL., < Gr. vpin-of, 
first, + L. rertebra, vertebra.] 
If. In Carus's nomenclature 
(1828), a rib regarded as a 
vertebral element developed 
to contain and protect the 
viscera, or organs of vegeta- 
tive life: correlated with <leu- 
tovertebra and tritorertcbra. 
2. A primitive, temporary 
vertebra; one of the series 
of segments which appear in 
pairs in the early embryo 
along the course of the noto- 
chord, and from or about 
which the permanent ver- 
Protozoa 
tebrse are developed. They soon disappear, 
being replaced by definitive vertebrae. 
protovertebral (pro-to-ver'te-bral), a. [(pro- 
tovertebra + -al.] Having the character of a 
protovertebra ; pertaining to protovertebrw : 
as, a protorcrtebral segment; a protovertebral 
portion of the notochord. 
Protovertebrata (pro-to-ver-tf-bra'ta), . pi. 
[NL. : see protovertelirate.] A hypothetical 
group of animals, assumed to have been the 
ancestral forms of the Vertebratfi. 
protovertebrate (pro-to-ver'te-brat), a. [< NL. 
*proh>i'ertebratiui,\prot<rrrrtfbr<i,<\.v.] 1. Pro- 
vided with or characterized by the presence of 
protovertebne : as, the protovertebrate stage of 
a vertebrate embryo. 2. Of or pertaining to 
the Prototertebrata. 
protovestiaryt (pro-to-ves'ti-a-ri), H. [< ML. 
protoreytiariiix, < Gr. frpdrrof, first, + ML. w- 
tiarius, the keeper of a wardrobe : see vestiary.] 
The head keeper of a wardrobe. 
Protmeitiary, or wardrobe keeper of the palace of An- 
tiochus at Constantinople. 
T. Warton, Hist. Eng. Poetry, I. IS'J. 
protovum (pro-to'vum), n. ; pi. protora (-va). 
[NL., < Gr. TTptJTOf, first, + L. orum, egg: see 
ovum.] An original or primitive egg ; an ovum 
or ovule in its first state, as when still in its 
Graafian follicle, or, in general, before its im- 
pregnation, when it becomes a cytula or parent- 
cell by fecundation with sperm ; or, in the case 
of meroblastic eggs, an undifferentiated female 
egg-cell before it acquires the mass of non- 
formative food-yolk which converts it into a 
metovum. 
protoxid, protoxide (pro-tok'sid), w. [< Gr. 
xpuTuc, first, + E. oxiil.] That member of a 
series of oxids which contains a single oxygen 
atom combined with a single bivalent atom or 
with two univalent atoms: applied only to 
oxids which are not strongly basic or acid. 
protoxylem (pro-to-zi'lem), 11. [< Gr. TTpuTof, 
first, + E. xylem.] In but., the first-formed 
elements of the xylem of a vascular bundle. 
Protozoa (pro-to-zo'tt), M. pi. [NL., pi. of Pro- 
tozoon.] Primordial or first-formed animals, 
or cell-animals ; protozoans: a subkingdom of 
Animalia or prime division of animals, con- 
trasted with Meta:oa, or all other animals col- 
lectively. The Protozoa are animal organisms con- 
sisting of a single cell, or of several cells not differen- 
tiated into tissues. This is the essential distinction 
between protozoan and metazoan animals, though no 
hard and fast line can be drawn around Protozoa to dis- 
tinguish them on the one hand from 1'rotophyta, and on 
the otherfrom Metazoa. The name }*rotozoa was first used 
by Goldfuss (1809) to include microscopic animals and also 
the polyps and niediiM<>. Siebold and Slanmus first used 
It in its modern signification as comprising and limited 
to the infusorians and rhizopods. Owen (1859) used the 
term Protozoa for a kingdom including diatoms, etc., 
and therefore synonymous with I'rotigta. The sponges, 
in the view (as held by W. Saville Kent, for example) 
that they consist essentially of an aggregate of choano- 
flagellate infusorians, are often brought under 1'rotozoa, 
though they have not only an ectoderm and an endo- 
derm, but also a mesoderm, and are therefore tissue- 
animals as distinguished from cell-animals. Excluding 
sponges, Protozita may be characterized as animals com- 
posed of a simple nearly structureless jelly-like substance 
called ttarcode, a kind of protoplasm, devoid of permanent 
distinction or separation of parts resulting from tissue- 
formation or histogenesis (though they may have very 
evident organs us parts of a single cell), without a perma- 
nent definitive body-cavity or any trace of a nervous sys- 
tem, no permanent differentiated alimentary system ex- 
cept in a most rudimentary state, and no inulticellulaj 1 
membranes or tissues. Nevertheless, there is really a 
wide range of variation or gradation of structure In these 
seemingly structureless animalcules. Some of the lowest 
forms are mere microscopic specks of homogeneous sar- 
code, of any or no definite shape. Such are moners. or 
representatives of a division Monera or Proteomuxa ; but 
it is not certain that all such objects are either Individu- 
als or species in a usual sense of these words. Among 
the lowest protozoans of which species and genera can 
be definitely predicated are the amoehlform organisms, 
which have a nucleus, and locomotory organs In the form 
of pseudopods, temporarily protruded from any part of 
the body, and which Ingest and egest foreign 'substance 
from any part of the body. Vast numlwrs of protozo- 
ans are of this grade of complexity, and with the simpler 
forms constitute a class, Ilhizopoda, including the normal 
amteboids and the fommlnlfcrs and radlolarians. For, 
though both these latter may have very complicated shells, 
tests, or skeletons, their sarcodous substance remains of 
a low and simple type. It is an advance in organization 
when a protozoan becomes corticate that is, assumes a 
form In which an outer harder ectoplasm and an inner 
softer endoplasm are distinguishable since this confines 
the sarcodous mass and gives it definite shape or form. 
This advance in organization is often marked by the ap- 
pearance of a nuclenlns or endoplastnle, besides the tin 
cleus or endoplast which most protozoans possess, by the 
presence of ilcthiite and permanent locomotory organs in 
the form of cilia orflagella, and finally try the fixation of ;i 
specialized oral oringcKtive area or moutli, in placeof thr 
one or several temporary vacuoles which serve as stom- 
achs in lower forma. Protozoans of this higher grade occur 
