

^. 





S 



f^. but ci/ '"i»' 



'^■^ goes 



ti 



ibre 



Penet 



s isfo 



rate \v> 



m I B, 



I 



■o^s, and V 



bs and evpn 



^'^ years' 

 continues for 



from i 



It 



a vetf 

 constitute 



r 

 e 



i 



external objects, 0, 

 continuance of ik 

 e occurrence of 

 >-Tsist in this 



miversal presence 

 ■ain water, may 

 r this green al«;i 



n and the Lub- 

 milar segmentatioi- 

 lichen-thallusisulti- 

 the soridia uii(lers» 



;tead of passin? 



The changes 

 >. Hicks prinoP^'' 





athattbesojjS 



. ; in ^''\\ls^<^ 



:e 



so CO 



Pr. 



# 



in cf P'^' .. 



APPENDIX D. 



Iv 



in Cladonia pyxidata^ though similar processes have been 

 watched in connection with the gonidia of other Lichens 

 belonging to the same and to different genera. 



When growing in a dry situation (or if the season is hot 

 and dry) the gonidia of Cladonia pyxidata behave in the 

 same manner as those already described of Parmelia and 

 Chlorococcus ; but, on the contrary, if the weather becomes 

 damp, if the plant grows in a damp situation, or even if 

 removed to one, then other and quite different changes 



ensue. 

 Under any one of such circumstances, Dr. Hicks says : — 



' The first change observable is that some of the segments 

 become enveloped by a layer of mucus, inside of which sub- 

 division still further proceeds, the portions in most cases pos- 

 sessing, after a little time, each a separate mucous envelope^. 

 Thus we have all the elements of a Gleocapsa (Kiitzing) 

 growth. At first, commonly, the subdivision is continued on 

 the binary plan, which may continue for some time/ Other 

 modes of subdivision, however, may follow. The early seg- 

 ments may separate from one another, each provided with 

 a mucous layer, but in others the mucous envelope of the 

 original cell does not dissolve away, though segmentation pro- 

 ceeds in its interior. Thus masses result, in which the Gleo- 

 capsiform cells have from one to three common envelopes, 

 and a condition is produced, as Dr. Hicks points out, similar 

 to Hassal's Ilematococcus rupest 'is. But, he says : — ' In the 

 same mass — the produce of the Clado7tia-9>ondl2i — will be 

 found every variety of subdivision, each form constituting 



smaller extent,' though 



these 



a mass of a greater or 



various products were not always indiscriminately mingled, 



^s if a particular kind having once commenced, it would, 



All the changes which are now being described are accurately 

 represented in PI. ii. of the ' Journ. of Microsc. Science' for i86d. 



