PAMPHAGUS. 



[ 576 ] 



PAPER. 



each cell ; tentacular disk circular, with a 

 single row of free tentacles. 



P. articula'a. The only species; olive- 

 green ; polypes ascidian. Freshwater ; dia- 

 meter of filaments about 1-30 to 1-20". 



BIBL. Johnston, Br. Zooph. 405 ; All- 

 man, Ann. N. H. xiii. 331, and Pr. Irish 

 Ac. 1843. 



PAM'PHAGUS, Bailey. A genus of 

 Rhizopoda allied to Lieberkuehnia. P. mu- 

 tabilis is amcebiform, covered with a delicate 

 elastic integument. Bailey, Amer. Jn. Soi. 

 xv. ; Pritchard, Inf. 551 ; Claparede et 

 Lachmann, Etudes, 465; Archer, Qit. M. J. 

 1871, 101. 



PANDORFNA, Bory (PI. 5. fig. 10). 

 A genus of Volvocineas (Confervoid Algae), 

 which we believe to be synonymous with 

 Eudorina. It exhibits a great variety of 

 forms, some of which have been described 

 under the name of P. Morum, others otEud. 

 eleyans. The most characteristic conditions 

 are represented in PI. 5. tig. 10. Pandorina 

 stands midway between Volvox and Ste- 

 plianosplicera, consisting of an ellipsoidal 

 translucent gelatinous sac, containing im- 

 bedded just within its surface, several zone- 

 like rows of green pear-shaped gonidia, 

 whose two cilia penetrate the gelatinous 

 envelope, and, hanging out free, move the 

 entire organism by their vibration. Two 

 distinct forms occur one with sixteen, the 

 other with thirty-two gonidia. Where 

 sixteen occur, there are four zones of four 

 gonidia, while where thirty-two exist they 

 stand in four zones of eight, with four at each 

 end(Pl. 5. fig. 10 a and 6). The gonidia 

 have a red spot and a vacuole, like those of 

 Gonium and Volvox. These two forms 

 occur together; and evidently the difference 

 arises simply from an additional binary sub- 

 division of the gonidia in the earlier stages 

 of development from the spore. They are 

 often so numerous as to tinge the water of 

 fresh pools green, like Volvox and Proto- 

 coccus. They occur of various sizes, from 

 1-80" downwards. 



These forms are multiplied vegetatively 

 by the conversion of each gonidium into a 

 family like the parent, each group acquiring 

 its special envelope and becoming free by 

 the solution of the parent-envelope. Two 

 corresponding forms also occur with the 

 above, with the sixteen or thirty-two goni- 

 dia closely crowded together, instead of 

 standing at wide intervals in the large 

 colourless envelope. 



The resting-spores are formed out of all 



or part of the gonidia of a family, after 

 conjugation (h'g. 139*, p. 205). The impreg- 

 nated gonidia soon acquire a stout special 

 coat, and their originally green contents 

 turn red ; they become free by the solution 

 of the parent-envelope. In germination 

 they turn green again, and by repeated 

 division of their protoplasm, form the new 

 families of sixteen or thirty-two, constitu- 

 ting the perfect plant. 



Fertilization of the gonidia has also been 

 described as being produced by tho action 

 of spermatozoids minute, fusiform, ciliated 

 corpuscles, produced in large numbers by the 

 subdivision of certain of the gonidia. 'This 

 seems doubtful. 



BIBL. Ehr. Inf. 53; Duj. Inf. 317; 

 Henfrey, Mic. Tr. 2. iv. 49; Fresenius, 

 Mus. Senckenb. ii. 187 ; Cohu, Nova Acta, 

 xxvi. 1 ; De Bary, Sot. Zeit. xvi., 8upp. ii. 

 73;Currey, Q. Mic. Jn. vi. 213; Carter, 

 Ann. N. H. 3 ser. ii. 237; Rabenhorst, 

 Ale/, iii. 99; Pringsheim, Monatsb. Berl. 

 Ak. 1869 ; Sachs, Bot. 258. 



PANNA'RIA, Del. A genus of Placodei 

 (Lichenaceous Lichens). Several species. 

 (Leighton, Lich. Fl. ]50.) 



PANOPH'RYS, DUJ. = FRONTONIA pt. 



P. chrysalis (PI. 31. fig. 55). Marine. 



BIBL. Duj. Inf. 491 -j Claparede & Lachm. 

 Etudes, 260. 



PANTOT'RICHUM,Ehr. A genus of 

 Infusoria. 



P. laffenula, E. (PI. 31. fig. 58). Body 

 ovate, equally rounded at each end, yellow- 

 ish ; tegument produced in front in the 

 form of a neck or truncate rostrum ; length 

 1-1080 to 1-580". 



BIBL. Ehrenberg, Inf. 247; Dujard. Inf. 

 388 ; Clap, et Lachra. Inf. 315. 



PAPER. A few general observations 

 only can be made under this head. Ordinary 

 paper, as is well known, was generally manu- 

 factured from rags of linen or cotton fabrics, 

 so that it consisted of a kind of felt of the 

 fibres of cotton or flax ; but in consequence 

 of the immense demand for paper, other 

 substances, such as straw, jute, esparto, the 

 pulped woody fibres of the poplar and pine, 

 are now largely used. The manipulation 

 to which the material is subjected, together 

 with the effect of frequent washing in the 

 case of rags, affects the characters of the 

 fibres to some extent ; and the cellulose is 

 in some cases already brought into that 

 state in which iodine colours it blue. The 

 addition of sulphuric acid and iodine colours 

 the fibres of most papers blue ; and care 



