872 GLOSSARY OF TECHNICAL TERMS. 



Pectinate. Lat. pecten, a comb. Divided into narrow segments like the teeth of a 

 comb. 



Pedunculate. Lat. pedunculus, a Httle foot. Provided with a stalk or pedicle. 



Peridium. Gr. perideo, I wrap round. The membranous outer wall of the spore- 

 capsule or sporangium of the Mycetozoa. 



Peristaltic. Gr. peristaltikos, drawing together all round. Applied to the circular 

 contractions from above downwards, exhibited by the intestines, and also in the 

 locomotion of many worm-like animals. 



Peristome. Gr. peri, around ; stovia, a mouth. The oral region with its accompany- 

 ing ciHa, as applied to the Infusoria. 



Peristomal. Gr. peri, around; sfotna, the mouth. Relating to the peristome or oral 

 region. 



Peritrichous. Gr. /^r/, around ; fhrix,ha.\r. Having hair or ciHa developed in the 

 form of a wreath or girdle round the body. 



Pharyngeal. Pertaining to or connected with the pharynx. 



Pharynx. Gr. pharunx, the throat or windpipe. As applied to the Infusoria, denoting 

 that part of the alimentary tract, sometimes with indurated walls, that immediately 

 succeeds the oral orifice. 



Phycochrome. Gr. phukos, sea-weed ; chroma, colour. The essential brown colouring 

 matter of the olive-tinted or Melanospermous sea-weeds. 



Phylogeny. Gr. pJiulon, tribe ; genos, lineage. That branch of biology which attempts 

 to deduce the ancestral history of an animal or plant from its ontogeny or individual 

 developmental metamorphoses. 



Phylum, Gr. phuloti, tribe. Stock or tribe. 



Phytophagous. Gr. plmton, a plant ; phago, I eat. Feeding upon plants. 



Planula. Lat. planula, a little plane. The flattened, mouthless, ciliated embryo of 

 many Coelenterata. 



Plasmodium. Gr. plasma, a thing moulded ; eidos, resemblance. The gelatinous proto- 

 plasmic mass, possessing distinct locomotive properties, formed by the coalescence of 

 the flagelliferous monadiform elements of the Myxomycetes or Mycetozoa. 



Plastids. Gx.plastos, formed. A term occasionally applied to unicellular organisms or 

 elements that possess the value of a simple cell. 



Plicate. 'LdX. pUcatus, folded. Disposed in pleats or folds. 



Polymorphic. Gr. polys, many ; morphe, shape. Exhibiting a diversity of outline, e.g. 

 Englena. 



POLYTHECIUM. Gr. polys, many ; theke, a sheath or case. Title conferred by the 

 author on the compound structure, consisting of many conjoint sheaths or lorica;, 

 developed by such infusorial types as Dinobtyon and Stylobryon. 



Preoral. Lat. prcB, before ; os, oris, mouth. The fringe of cilia developed in front 

 of the mouth of certain Oxytrichidae. (See woodcut, vol. ii. p. 760.) 



Proboscidiform. \.2X. proboscis, a trunk ; for7na, form. Having a trunk-like aspect. 



Proglottids. Gr. pro, before ; glottis, the opening into the windpipe. The detached 

 sexually mature segments of a tape-worm, Tcenia. 



Proteinaceous. Gr. proios, first. Having a composition analogous to or containing 

 Protein. 



Protein. Gr. protos, first. A nitrogenous substance analogous to fibrin, manufactured 

 by plants out of inorganic compounds, and upon which all animals are dependent for 

 food, and for the sustentation of their vital functions. 



