452 THE BEGINNINGS OF LIFE. 



dence adduced by Dr. Braxton Hicks as to the extreme 

 modifiability of the simplest forms of Algiie, and also as 

 to the relationship which he, Itzigsohn, and others have 

 shown to exist between these forms of life and Lichens. 

 This and much other information tends to show that 

 Lichens and Algse are mere different modes of growth 

 which may be assumed by one and the same matter 

 when it undergoes internal changes — either ^spon- 

 taneously' or in response to alterations in external 

 conditions'. It was also ascertained by the same ob- 

 servers that green elements thrown off from the radicles 

 or leaves of mosses might live and vegetate for an 

 indefinite period, after the manner of one or other of the 

 Algae, and that then, after a time, many of such forms 

 might (under suitable conditions) develop ^ soridia,' con- 

 stituting the commencement of a new phase of growth, 

 which gradually unfolds into one or other of the com- 

 mon Lichens 2. But whilst it has been long known 

 that Mosses were constantly developed from similar 

 confervoid modes of growth, it had not been thoroughly 

 established that they might arise from Confervas which 



^ See p. 164. Quite recently I have seen in a vessel containing an 

 old and partly-decolourized Euglena-pellicle, the whole upper surface 

 become, almost simultaneously, covered with a dry pulverulent growth 

 of Chlorococcus, from which Lichens a're so apt to develop. The 

 pellicle was thick, and its upper surface dry, whilst for three weeks 

 before the appearance of the Chlorococcus the vessel containing it had 

 been covered with a bell-jar. 



^ These views are also supported by the observations of Mr. Metcalfe 

 Johnson. (See ' Monthly Microsc Journ.' of Nov. 1871.) 



