PER 



313 



PER 



perisarc, n., pWi-sdrk (Gr. peri, 

 round about ; sarx, flesh), a 

 general term for the chitinous 

 envelope secreted by many of the 

 Hydrozoa. 



perisome, n., pZrti-sdm (Gr. perl, 

 round about ; soma, body), the 

 coriaceous or calcareous integu- 

 ment of the Echinodermata. 



perisperm, n., p&r'-i'Sperm (Gr. 

 peri, round about ; sperma, 

 seed), in lot., the innermost 

 envelope of the seed ; the albu- 

 men or nourishing matter stored 

 up with the embryo in the seed : 

 perispermic, &.,p$r'i>sperm''ik, of 

 or pert, to the perisperm. 



perispheric, a., pe'r'i-sfer'ik, also 

 perispherical, a., -sf^-ik-dl (Gr. 

 peri, round about ; sphaira, a 

 sphere), having the form of a 

 ball ; globular. 



perisporangium, n., p$r'$-8pdr- 

 dnf'i-um (Gr. peri, round about ; 

 spora, seed ; anggos, a vessel), 

 in bot. 9 the indusium of ferns 

 when it surrounds the Sori. 



perispore, n., petfi-spor (Gr. peri, 

 round about ; spora, seed), the 

 membrane or case surrounding a 

 spore ; the mother^cell of spores 

 in Algae. 



Perissodactyla, n. plu,, p%r>is'sd- 

 ddWttt-d (Gr. perissos, uneven ; 

 daktulos, a finger), the hoofed 

 quadrupeds, or TJngulata, in 

 which the feet have an uneven 

 number of toes. 



peristaltic, a., p$r f -i-8t&lt'>ik (Gr. 

 peristaltiJcos, drawing together all 

 round from peri, round about ; 

 stello, I send), applied to the 

 peculiar worm-like motion of the 

 intestines by which their contents 

 are gradually forced downwards ; 

 circular contraction from above 

 downwards. 



peristome, n., p^is-tom (Gr. 

 peri, round about ; stoma, a 

 mouth), in lot., the ring of 

 bristles or toothed fringe situated 

 around the orifice of the seed- 

 vessels in mosses ; the opening 



of the sporangium of mosses after 

 the removal of the calyptra and 

 operculum ; in zool., the space 

 between the mouth and the mar- 

 gin of the calyx in Vorticella, 

 or between the mouth and the 

 tentacles in a sea-anemone ; the 

 lip or margin of the mouth of a 

 univalve shell : peristomatic, a., 

 p&T'te'-ttim'&tiiki of or pert, to a 

 peristome ; in bot. 9 having cells 

 surrounding a stoma. 



perithecium, n., per'-i-tlie'-shi-tim, 

 perithecia, n. plu.,p&r'i-the'shi-d 

 (Gr. peri, around ; theke, a box 

 or case), in bot., the envelope 

 surrounding the masses of fructi- 

 fication in some Fungi and 

 Lichens ; a hollow conceptacle in 

 Lichens, containing spores, and 

 having an opening at the end, 



peritonaeum, or peritoneum, n., 

 pVr'-i'tpn-e'-um (Gr. peritonaion, 

 what is stretched round or over 

 from peri, round about ; teino, I 

 stretch), a serous and smooth 

 membrane which lines the whole 

 internal surface of the abdomen, 

 and envelopes more or less com- 

 pletely the several parts of the 

 viscera, retaining them in their 

 proper places, and at the same 

 time allowing them to move 

 freely when required: peritoneal, 

 a., per''i>ton-e''dl, of or pert, to 

 the peritoneum : peritonitis, n., 

 p^i'ton'lt'-iSf inflammation of 

 the peritoneum. 



peritropal, a., pe'r-it'-rtip-al, also 

 peritropous, SL^pe'r-it'-rdp-us (Gr. 

 peri, round about ; trope, a turn- 

 ing), in bot., applied to the axis 

 of a seed perpendicular to the 

 axis of the pericarp to which it 

 is attached. 



perityphlitis, n., ptr'-t-ttf-lU'-fs 

 (Gr. peri, round about ; tuphlos, 

 blind), inflammation around the 

 caecum. 



perivascular, a., 

 (Gr. peri, round about ; L. vasc- 

 ulum, a small vessel), applied to 

 canals which surround and en- 



