rOLYTRICIIUM. 



[ 625 ] 



rOLYZOA. 



cence, composed of scale-like leaves and 

 pavaphyses suvrounding a uuniber of subu- 

 late sacs constituting tiie aniherklia. The 

 male tlowersof P. commune ^uiuperinum,Sic. 



Fig. 600. 



Polytrichum commune. 

 Capsule with operculum. Section of young capsule 

 Magnified 10 diameters. showing the plaited spo- 



" rangial membrane. 



are found everywhere on heaths in spring. 

 The antheridia'may be readily extracted un- 

 der a simple lens, and, when placed iu vrater 



Polytrichum commune. 



Fragment of peristome. Columella with section 



Magn. 100 diams. °^ ^^^ apophysis. 



Magn. 25 diams. 



under the compound microscope, soon (if 

 ripe) hurst at the summit and discharge the 

 spermatozoids ; these usually escape still 

 enclosed in their parent cells, which when 

 first discharged cohere in a gelatinous mass ; 

 hut the ciliated spermatozoids (PI. 40. fig. 

 33) escape and swim actively in the water. 



They require at least an eighth object-glass 

 for examination ; and the cilia are seen most 

 clearly after drying the object, or treating 

 it with tincture of iodine. 



Fig. 604. 



Fig. 605. 



subkingdom 



Poljiirichum commune. 

 Male inflorescence. Innovation from male 



One half nat. size. inflorescence. 



Magn. 5 diams. 



BiBL. Wilson, Bryol. Brit. p. 205 et seq. ; 

 Tburet,. Ann. Sc. Nat. 3. xvi. 26, pi. 14. 



POLYZO'A or BRYOZOA.— A class of 

 Animals, belonging to the 

 Mollusca. 



Char. Polypiform, aggregate ; indi-^-idual 

 bodies microscopic, contained in horny or 

 calcareous cells, often connected by tubular 

 stems, forming a usuallj' branched zoary ; 

 mouth stUTOinided by long, ciliated, uncon- 

 tractile tentacles ; mouth and anus separate, 

 but near each other. Marine and fresh- 

 water. 



They are found everywhere on the sea- 

 shore, either rooted to, or forming a crust 

 upon submerged rocks, stones, shells, &c. 

 The individual is called a polypide ; and 

 the aggregate or colony constitutes a 

 coenoicium or polyzoarium ; it is usually 

 of a whitish or brownish colour, of a 

 horny or calcareous textvire, and consists 

 either of cells or cups simply aggregated 

 (PI. 41. figs. 17, 20), or connected by tubu- 

 lar stems, and often- arranged in elegant 

 plant-like forms (PI. 41. fig. 5 a). The 

 stems are divided into compartments by 

 perforated septa (PL 41. fig. 5/), through 

 which thread-like filaments of the sarcode 

 pass. 



2s 



