1 64 THE BEGINNINGS OF LIFE. 



mentary and ulva-like Algae which were, and are still 

 regarded by various naturalists as so many distinct and 

 constant species. On the other hand, they have also 

 taught us that these supposed autonomous forms are 

 derivable either from Lichens or other Algae, that they 

 are capable of vegetating for months in one or other of 

 these algoid states, or in several of them successively, 

 whilst at last under suitable conditions such modes of 

 growth may lapse again into those characteristic of 

 Lichens or Mosses. Green corpuscles (gonidia) thrown 

 off from a single Lichen have been seen by Dr. Hicks 

 to assume the forms and mode of growth characteristic 

 of no less than twenty-three supposed species of Algae. 

 On the other hand, gonidia thrown off from an Alga or 

 from a Moss are capable of going through any similar 

 number of modes of growth, according as the conditions 

 to which they are subjected undergo variations. Speak- 

 ing generally, heat and drought were observed to be 

 favourable to their development into Lichens, though 

 in damp places some grow and multiply prodigiously 

 in the form of Algae, whilst others seem to develop 

 into different forms of Moss. In water the gonidia 

 may either continue to grow after the fashion of 



to indicate that green protoplasm manifests itself almost as readily 

 under certain circumstances, as colourless protoplasm does under others : 

 and the same may be said concerning the red protoplasmic masses 

 (Palmell(B) which in the form of so-called ' blood spots ' have at various 

 times been known to make their appearance upon all kinds of provisions. 

 (See Lindley's ' Veget. Kingdom,' p. 446 ; and Hecker's ' Epidemics of 

 Middle Ages,' pp. 205-207.) 



