PLAXKTOXIC 







helminthes, echinoderms, acephala, gasteropods, etc. 

 Plankton may be Monotonic (simple tow-stuff), 

 ving a homogeneous composition, or it may be 

 Polymixic (mixed tow-stuff), composed of organisms 

 of different species and classes in such a way that no 

 one form or group of forms composes more than oue- 

 half of the whole volume. 

 Planktonic (plank-ton' -ik ) [plankton, the drifting life 



of the sea]. In biology, pertaining to plankton. 

 Planoblast (plan'-o-biast) [-/Avoc, wandering; 3/ac- 

 germ]. In biology, the free swimming medusoid 

 bud, or gonophore of a gymnoblastic hydrozoan, as dis- 

 tinguished from the sedentary bud or hedrioblast, q. v. 

 Planoblastic iplan-o-blas'-tik) [rf.avoc, wandering; 

 - . germ]. In biology, pertaining to a piano- 

 blast. 

 Piano-cellular (plan-o-sel' -u-lar) [planus, flat; cellula, 

 11]. Flat-celled. 



o-concave, Plano-convex (pla' - no- kon- kdv', 

 no-kon-veks'). See Lens. 

 Planodia ( plan-o' -de-ah) [-x/Avrj, a wandering ; 666c, 

 way]. Any false or artificial passage made by an 

 trument. 



ogamete (plan' -o-ga-mef) [-/Avr], a wandering ; 

 uuv, to marry]. In biology, a ciliated form of 

 ete, or protoplasmic conjugating body ; a zoo- 

 mete. Cf. Gamete. 

 Planogastrula (plan-o-gas' -tru-lah) [planula (— ?Avoc, 

 wandering) ; gastrula, a two-layered, saccular germ 

 . belly)]. The name applied by Hneckel in his 

 trxa theory to that stage in the evolution of the 

 strula from the planula, characterized by the hol- 

 wing out of the endoderm of the latter, 

 omania ( plan-o-ma' -ne-ah) [-/Avoc, wandering; 

 madness]. A morbid and insane desire for 

 wandering. 

 Plant [planta. a plant]. Any member of the vegetable 

 kingdom. P., Aerial, P., Air, a plant which derives 

 nourishment from the air. P., Carnivorous. 

 >nym of P. , Insectivorous. P., Flowering. See 

 nerogam. P., Flowerless. See Phanerogam. 

 P.. Insectivorous, a plant which entraps and digests 

 insects: e.g., Drosera rotundifolia. P., Pitcher. 

 See Pitcher-plant. P., Sensitive, Mimosa pudica, 

 and other species, the leaves of which contract when 

 they are touched. 

 Planta (plan'-tah) [L.]. I. A plant. 2. The sole of 



the foot. P. pedis, the sole of the foot. 

 Plantago (plan-ta'-go) [L., gen. plantaginis']. The 

 leaves of P. major and P. lanceolata, or common 

 ribbed grass, or plantain. The bruised fresh leaves 

 are a popular remedy for hemorrhage, painful abra- 

 sions of the skin, burns, erysipelas, etc. Dose n\v-xv. 

 Unof. 

 Plantain (plan'-tdn) [ME., plant eyrie, plantain]. I. 

 >e as Plantago. 2. The tropical plant Musa 

 j paradisiaca, and its fruit ; they are of great economic 

 importance in the tropic regions as a food for mankind. 

 Plantar [plan' -tar) [plantaris ; planta, sole of the 

 i foot]. Pertaining to the sole of the foot. P. 

 Aponeurosis. Synonym of P. Fascia. P. Arch, 

 a name given to one of the parts into which the 

 external plantar artery is divided. P. Arteries. See 

 Arteries, Table of. P. Fascia, the dense, triangular- 

 shaped aponeurosis occupying the middle and sides 

 af the sole of the foot beneath the integument. P. 

 Muscle. See Muscles, Table of. P. Nerve. See 

 . Table of. P. Reflex. See Reflexes, Table 

 of. P. Tubercle, the tubercle of the first metatarsal 

 bone, and to which the tendon of the peroneus longus 

 muscle is attached. 



1111 



PLASMA 



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Plantaria (plan-to' -re-ah). Synonym of Dengue. 



Plantaris ( plan-ta'-ris) [planta, sole of the foot]. See 

 Plantar. P. Muscle. See Muscles, Table of. 



Plantigrade ( plan' -tig-rdd) [planta, sole; gradi, to 

 walk]. Bringing the entire length of the sole of the 

 foot to the ground in walking, as is seen in the bear 

 and in certain birds which apply the back of 

 the tarsus as well as the toes to the ground in walking. 



Plantivorous (plan-tiv'-o-rus) [planta, plant; vorare, 

 to devour]. In biology, living on plants, e.g., cater- 

 pillars. 



Plantosseous (plan-tos'-e-us) [planta, sole ; osseosus, 

 bony] . Both plantar and interosseous. 



Plantosseus (plan-tos'-e-us) [planta, sole; osseosus, 

 bony]. Any plantar interosseous muscle. 



Plantula ( plan' -tu-lah) [planta, the sole of the foot : 

 //., Plant ubz\. In biology, the appendage, generally 

 cushion-like, between the claws of certain insects ; it 

 corresponds to the structure in other forms called 

 onychium and pulvillus. 



Plantular (plan'-tu-lar) [plantula, a little plant]. 

 Pertaining to a plantula. 



Planula (plan' -u-lah) [-7Avoc, wandering: //., Plan- 

 ula\. In biology, the globular or oval, free-swim- 

 ming, two-layered, solid larva of certain of the Porif- 

 era and Calenterata. It is destitute of a mouth or 

 blastopore, and succeeds the blastula in those meta- 

 zoans in which gastrulation takes place by immigration 

 and delamination, instead of by invagination. The 

 planula is succeeded by the Planogastrula and this in 

 turn by the gastrula stage proper, with its blastopore. 

 Salensky describes a three-layered planula in the 

 Rotatoria and other forms. The term planula was 

 first applied by Dalzell to the motile larvae of certain 

 hydrozoans (" zoophytes "), but it has come to have a 

 broader application. Planula may be regarded as the 

 ancestral form of the Cnidaria. It appears to corres- 

 pond to the parenchymula of Metschnikoff. 



Planulan (plan' -u-lan) [rr/Avoc, wandering]. A plan- 

 ula. 



Planular ( plan' -u-lar) [^/Avoc, wandering]. Pertain- 

 ing to a planula. 



Planuliform (plan' -u-lif-orm) [rr'/avoc, wandering; 

 forma, form]. In biology, resembling a planula. 



Planuloid (plan'-u-loid) [-/Avoc, wandering; eldor, 

 like]. Resembling a planula. 



Planum (plan'-um) [L.]. A plane or surface. 



Planuria (pla - nu'- re - ah) [^/Avoc, astray ; ovpov, 

 urine]. The discharge of urine through passages 

 other than the normal duct. 



Plaque (plak) [Fr.]. A plate, patch or spot. P., 

 Blood. See Blood-plaque. P., Mucous, P. mu- 

 queuse [Fr.]. Mucous patch; condyloma latum. 

 Plaques, Pterygoidean. See Pterygoidean. Ps., 

 Sclerose en. See Sclerose en plaques. 



Plasm (plazm) [-/Aaua, a figure molded from clay or 

 wax]. In biology, same as Plasma. P., Germ, a 

 distinct form of protoplasm acting as the vehicle of 

 inheritance. 



Plasma (plaz'-mah) [-/Aaua, a thing molded]. I. 

 The original undifferentiated substance of nascent 

 living matter. The primordial protoplasm or " physi- 

 cal basis of life. ' ' 2. The fluid part of the blood and 

 the lymph ; the blood and lymph exclusive of the 

 corpuscles. See Blood-plasma and Liquor sanguinis. 

 P. -cells of Waldeyer, the highly vacuolated connec- 

 tive-tissue cells, irregular, extended or spindle-shaped. 

 They probably bear a somewhat constant relation to 

 young tissues in which the formation of new blood- 

 vessels is still progressing. P. -fibrin, Landois' term 

 for fibrin formed in the usual way, as distinguished 

 from stroma-fibrin, or that formed directly from stroma. 



