THE SIMPLEST FORMS OF LIFE 45 



doubted progenitors of the higher plants, their evident 

 relationship with tile Volvocinese points to the latter as 

 the starting point for the whole series of green plants 

 above the Schizophycese. 



Summary 



We have seen that at the bottom* of the two great 

 series of organisms — plants and animals — there is an 

 assemblage of extremely simple forms, many of which 

 have not reached a stage of differentiation where it is 

 possible to say that they are either plant or animal. 

 Of these the Slime-moulds and Monera represent two 

 evidently related branches of a common stock, which is 

 perhaps, on the whole, more animal than vegetable in 

 its nature. The slime-moulds, however, owing to their 

 aerial habits have developed fructifications which super- 

 ficially closely resemble the sporangia of many higher 

 plants, and the spores are also plant-like in character. 

 These spores on germinating give rise to uniciliate, 

 monad-like zoospores, which closely resemble the lower 

 flagellate infusorians and suggest a relationship with 

 them. The relationship of the slime-moulds to the 

 other plants must be considered extremely doubtful. 



The second group of low plants, the Schizophytes, 

 while certainly to be considered as plants, are neverthe- 

 less very widely separated from any forms above them, 

 and their connection with these higher plants must 

 also be considered as, at least, uncertain. Whether 

 the forms with chlorophyll among the Schizophytes are 

 to be considered as the primitive types from which the 

 bacteria or those forms without chlorophyll have been 



