49 H 



EXPLANATION OF TERMS. 



Pellicula. The separable rind-layers of some 

 compound sporophores. Same as cutis. 



Penicellate. Having the form of a pencil 

 of hairs. 



Periderm. The cork-cambium and its 

 products. 



Peridiolum. In Nidularieae : chamber 

 of the gleba, forming a nest of spores, 

 free or attached by a funicle within the 

 peridium of the sporophore. 



Peridium. General term for the outer en- 

 veloping coat of a sporophore upon which 

 the spores develope in a closed cavity. 

 I nUrcdineae it envelopes the aecidium and 

 is also termed pseudoperidium, para- 

 ID hyses-envelope. In Gastromycetes 

 termed also uterus, and maybe differen- 

 tiated into peridivim externum (outer 

 peridium), the outermost layer which 

 opens in various ways and separates from 

 the peridium internum (inner peri- 

 dium) a layer directly enclosing the gleba. 



Peridium externum. See peridium. 



Peridium internum. See peridium. 



Periphysis. In Pyrenomycetes : sterile 

 capilliform hyphal branch projecting 

 from the wall of the pyrenocarp where 

 there is no hymenium into its cavity. 



Periplasm. In Peronosporeae: protoplasm 

 in the oogonium and the antheridium 

 which does not share in the conjugation. 

 Comp. gonoplasm. 



Perithecium. Same as pyrenocarp. 



Phototactic. Taking up a definite position 

 with reference to the direction of incident 

 rays of light. 



Phylogeny. Development of a species or 

 larger group. 



Pileus. In llymenomycetes : primarily, 

 the conical or dome-shaped upper portion 

 of the compound sporophore bearing a 

 hymenium on its under side ; now ex- 

 tended to all compound sporophores 

 in which the hymenium looks to the 

 ground. Same as cap. 



Pityriasis versicolor. Disease of the 

 skin caused by Microsporon furfur, Rob. 



Plasmodium. In Mycetozoa: body of 

 naked plurinucleated protoplasm exhi- 

 biting amoeboid motion. 



Plasmatoparous. In Peronosporeae : 

 forms are plasmatoparous when in ger- 

 mination the whole protoplasm of a goni- 

 dium issues as a spherical mass which at 

 once becomes invested with a membrane 

 and then puts out a germ tube. 



Plastid. Small variously shaped portion 

 of protoplasm of a cell differentiated 

 as a centre of chemical activity. 



Pleomorphism or Pleomorphy. The 

 occurrence of more than one independent 

 form in the life cycle of a species. 



Pleuroblastic. In Peronosporeae : forms 



producing vesicular lateral outgrowths 

 serving as haustoria are pleuroblastic. 



Pluricellular. Composed of two or more 

 cells. 



Plurisporous. Having two or more spores. 



Podetium. In Cladonieae : stalk-like or 

 shrubby branched outgrowth of the 

 thallus bearing exposed hymenia. 



Pollinarium. Same as cystidium. 



Pore, (a) In Pyrenomycetes: sameasostiole. 

 (b) In Hymenomycetes : same as tubulus. 



Primary lamella of spore. Outermost 

 layer of the coats of a spore representing 

 the original delicate wall of the primordial 

 spore. 



Primordium. First beginning of any 

 structure. 



Proearp. An archicarp with a special 

 receptive apparatus, the trichogyne. 



Promycelium. Short and short-lived 

 product of tube-germination of a spore 

 which abjoints acrogenously a small 

 number of spores (sporidia) unlike the 

 mother-spore and then dies oft. 



Prosporangium. In Chytridieae : vesi- 

 cular cell the protoplasm of which passes 

 into an outgrowth of itself, the sporan- 

 gium, and becomes divided into swarm- 

 spores. 



Prothallium. A thalloid oophyte or its 

 homologue. 



Prototballus. Same as hypothallus. 



Pseudoparenchyma. Symphyogenetic 

 cellular tissue. 



Pseudoperidium. See peridium. 



Pseudopodium. In Mycetozoa: a pro- 

 trusion of the protoplasm of an amoeboid 

 body which may be drawn in or into which 

 the whole mass may move. 



Purring (stiiuben). Sudden discharging of 

 a cloud of spores. 



Pullulation. Same as sprouting. 



Pulvinate. Having the form of a cushion. 



Pycnidiophore. Compound sporophore 

 bearing pyenidia. 



Pycnidium. In Ascomycetes : a variously 

 shaped cavity resembling a pyrenocarp 

 formed on the free surface of a thallus 

 and containing gonidia which are termed 

 pyenogonidia. See receptaculum. 



Pycnogonidium. Gonidium produced in 

 a pycnidium. Same as pyenospore, 

 stylospore. 



Pyenospore. Same as pycnogonidium. 



Pyrenocarp. Cup-shaped ascocarp with 

 the margin incurved so as to form a 

 narrow-mouthed cavity. Same as peri- 

 thecium. 



Receptacle (receptaculum). Term of 

 varying .signification, most usually imply- 

 ing a hollowed-out body containing other 

 bodies. Has the following special appli- 



