HICK.S_, ON GONIDIA OF LICHENS. 31 



sesses every cliaracter of tliat genus) ^ and Sorospora virescens, 

 Hassall {Microhaloa, Kiitzing) . 



Distinctions dra-vvn from a defined or undefined condi- 

 tion, either at first or subsequently, of the mucous portion 

 of the mass, 1 hold, as the result of numerous observations, 

 to be vakieless as a specific character, and the same may be 

 said of the persistence of the parent mucous envelope to the 

 second or third generation, such as forms the character 

 of Hcematococcus, Agardh {Gleocapsa polydermatica, Kiit- 

 zing), for in the plate accompanying this paper, and in that 

 illustrating Sachs' paper,"^ every variety may be seen so inti- 

 mately blended, that one can, by no possibility, deny their 

 common origin. 



AVhether Palmoglcea Brebissonii, which may be frequently 

 seen conjugating, be identical with the Cladonia-Palmoglcea, 

 requires further observation to determine. The remainder of 

 the British species of Palmoglcea or Coccochloris can certainly 

 be produced from Cladonia. Nor do I consider the size of the 

 cell of any importance as a specific character. From the re- 

 marks I have already made, and which I repeat here, it may be 

 noticed, that the size of cells in a state of subdivision, how- 

 ever produced, depends on the rapidity of the segmentary 

 process compared with that of the growth of the individual 

 cell. When the former process is very active, then the 

 resulting produce is small ; but when it proceeds slowly, 

 then the individual cells are larger, and continue to grow (so 

 long as the segmentary process is kept in abeyance) till they 

 arrive at full maturity. 



As far as my researches have extended, the following 

 forms, hitherto distinguished as species, have been observed 

 to spring from the soridium of Cladonia pyxidata : 



KUTZING. 



Gleocapsa polydermatica. 

 „ granosa. 



,j aruginosa. 



* Op. cit. 



