TECJI N IC A L M VCUL()(. V 



SECTION X 



KUDl.MENTS OF THE (JENEKAL MulU'lluLOGY AND 

 PILYSIOLl^C.Y OF TUF KF.M V( 'KTES. 



ClIAI'TKi; XXXIX. 

 GENERAL MORPHOLUCiV. 



,^ 217.— Articulation of the Thallus. 



ALREAnv in the lirst volunie (§ 22) the uh^n- and the fuiij^i 

 wore arnuiged in :i single giouj), that of the Thallophytes, in 

 contradistiiietiDn to all other plants, the latter Itciiig rl;i,-.setl in 

 the groiiit <>i Cormophytes. Tlie distinguishing chaiucteristics 

 of these two groups were stilted to be the absence in the former, 

 ami the jiresonee in tlie latter, of an articulation of the body of 

 the individual organism into leaf and stem. At the .sjuue time, 

 it was mentioned that the corporeal form assumed by the 

 ThaUnpliiit' .<, and dilTering fundament;illy from the connus of 

 tlie ('i>nii(i}>lii/f'!<, has receiveil the general name of thallus. Tliat 

 intei'motliate forms between these two types should exist, and 

 that the tlialhis «)f tlie highest 'J'/i'il/op/ii/tfs should approximate 

 to the cormus of the lowest L'oriiioi>/ii/h','i, is perfectly natunil and 

 in accordance with the general laws of phylogenetic evolution. 



Although the fungi, the only class of T/iaJiopIi i/tes wilh which 

 we are now concerned, do not exhibit division into leaf and 

 stem, their thallus is not entirely ilestitute of all articulation. 

 True, in one of the two chief divisions of the fungus family, the 

 Schizoinycetea, the articulation of the thallus is pnictically un- 

 discernilile. the indiviilual organisms taking the form t>f globular 

 or oval cells, or straight or bent rods of variable length. Should 

 any extensive development of tlu» thallus occur, this mav almost 

 invariably be rt>garded as either a malformation preceding 

 death — '•.;/. the branching of bacteroids (,^ 195) and liactvrntm 

 aceti {% 211) — or as an assemblage of several individual orgjin- 

 isms giving rise to a deceptive appeanmce tif articulation, as in 

 the c^ise of Chvlothrij- (^ 197). Again, in many species of 

 bacteria, the colonies known as zoogliea seem to exhibit a more 

 or less well-developed articulation ; but these cannot be con- 

 VOI„ II. A 



