24 Sl'OUHS AND TIIALLIDIA. 



in a brood-body ol" tho kind is limitod to t.wo, an is iho ciiso in tlu> so-palled 

 " toleiitosporea " of t.ho l\us( -Fungus; whilst those of Floridoivi soniotiuies hiivo 

 lour cells and aro known as " totrasporos " Ai:;nin, in othor ca.sos hundrods of 

 colls aro assoi'iatod togothor to i'onii a. (halliiliuiu. an insfcanoo of whioli is afi'onlod 

 by the brood-body or gonuna ol" Mairhaniia (see tig. 196 i-*'"). The " soredia. " of 

 Lichens must also be brought under this hoad — by the term soi-odia boiug undor- 

 stood certain bodies which arise upon the tlialli of Liphetis and consist of one or 

 more green cells wrapped in a net-work of colourless hyphai (see vol. i. p. 2'IH). 



¥ig. 107. — l''<>nmii:lon of 'rliallKlIn In l.lio colls of lltitlmiliclyoii iiin! In tlloHO of I'filiimlnnii 



« Wutoi'-Not (Ilydndwtyon ulrinilimiiiii). iiiitunil eizo, » A plooo of tlio Wiitor-Ncit; x 60. », *, » Uuvolopmoiit nml oBiiiiiii) of 

 li roUnilato timllldlum ; X 800. " reitiitHlrtnn j/iamilaluni ; duvolopinoitt unil uHunpu of blinllliltii ; the Ughtly-dottoil ooll 

 uhamborB ulroady vnuatod. ', b ThulUdiii of J'odiaHtrum ftftor tliolr uHunpo ; x "'to 



Thallidia may originate in the interior of a (^(*ll-cavity of the pal•(^nt-plant 

 and escape in the form of complete, though extr(^^llely minute, cell-aggr( "gates. 

 Instances of this are ad'onhMl by the Waier-Net {IJydroiiicijion utriculoaum), 

 which is shown in fig. 1 97°, and by I'ciliaHiruim, granulatum (lig. 197"), n,n 

 organism of frequent occurrence in pools. The alternative method of forination 

 of thallidia is by the severance of groups of supiu'flcial cellB, which, after an 

 interval of peregrination of variaWo durartion farSten on to Home spot or othor 

 and Found ;., new colony. In many Liverworts and Mosses special pockets and 



