122 



THE THEOKY OF EVOLUTION 



constitution of the separate tissues (conduction, as- 

 similation, protection, etc.), and according to the 

 reproductive arrangements. 



Warming l establishes five series. 

 1. Thallophyta or Sessile Plants. One or more 

 celled plants of simple construction, 

 almost always without limbs in the 

 root, stem, and leaves (such an 

 undivided plant body is styled 

 Thallus), and always without vas- 

 cular bundles 2 Algae, Fungi, and 

 Lichens. 



2. Bryophyta or Mosses. Small 

 plants with thallus or leaved stalks, 

 but without true roots 3 and with 

 vascular bundles. The group of 

 Mosses is sharply differentiated from 



FIG. 25. A Moss 

 Hypnum Purum. k, 

 the spore capsule , ,, ,, 



with its stalk, seated the following groups by the peculi- 



on the ' moss plant- 

 let ' and produced 



from a fertilized 

 ovum. 



arity of its reproductive changes. 

 The green moss plant that is 



what the layman generally under- 

 stands by ' moss ' produces in separate receptacles 

 both ova and motile antherozoids. The ova receptacles 

 are called archegonia, those of seed cells antheridia. 



1 Handbuch der systematischen Botanik, German edition, Berlin, 1902, 

 p.l. 



2 Vascular bundles are essentially bundles of conducting tubes for the 

 transport of water and the dissolved earthy salts contained therein to 

 the leaves and other organs. 



3 ' True ' roots i.e. roots with varied tissues. The Mosses have only 

 ' Rhizoids' i.e. threads formed of like rows of cells or even only of undivided 

 protoplasmic tubes. Rhizoids are therefore imperfect ' pseudo ' roots. 



