HICKS^ ON GONIBIA OF LICHENS. 15 



ing it. The F. V. of PL lanceolatum is that of a typical 

 member of the genus^ and is, therefore, not constricted in the 

 middle. 



Hab. Cresswell and Druridge Bay, plentiful. 



Contributions to the knowledge of the Development of the 

 GoNiDiA of Lichens, in relation to the Unicellular 

 Alg^. By J. Braxton Hicks, M.D..Lond., F.L.S. 



Fasciculus II. 



Cladonia. 



In the former fasciculus I endeavoured to show that the 

 green cell-growth everywhere covering trees, walls, palings, 

 &c., which was commonly called " Chlorococcus,^' and 

 ranked as an alga, was really, as had been suspected by 

 some botanists, the gonidia of lichens, which, for an inde- 

 finite time, continuing to undergo segmentation, ultimately 

 extended over considerable surfaces. I also showed that the 

 lichen-gonidium and the chloj'ococcus-gonidium both went 

 through the same changes of segmentation, and ultimately, 

 by the production of a fibre, became a soridium, within 

 wlvich, again, certain conditions of segmentation went on till 

 it became a thallus in miniature. I mentioned that, though 

 these were the changes common to the generality of lichens, 

 yet that there were some notable exceptions, one of the 

 most remarkable being that found in the subject of the 

 present contribution. 



Although the following remarks have reference princi- 

 pally to Cladonia pyxidata, yet it must not be supposed that 

 the changes are confined to it, for I have found them in at 

 ^ least two other species ; besides which, as will be again 

 noticed, they are to be found in other lichens of a diff'erent 

 genus. I had proceeded some way with these observations 

 when I had the pleasure of reading a communication on the 

 same subject in the ' Botanische Zeitung' (January 5th, 1855), 

 by J. Sachs, accompanied by figures, in which he pomts out 

 the origin of Gleocapsa from Cladonia pyxidata. He has 

 noticed it as prpceeding from the ends of the felted fibres on 

 the surface of the thallus. My observations go further than 



