PART I 



THALLOPHYTA. The Lower Plants. 



The various main groups of plants which, owing to 

 the absence of vascular tissue, show a superficial similarity 

 of structure are often arranged under two heads, viz. as 

 Algae and Fungi, omitting here for the present the 

 lichens. This distinction is, however, mainly based on 

 the presence or absence of chlorophyll ', without sufficient 

 regard to relationship as evinced by their mode of repro- 

 duction. As some fungi are evidently closely related to 

 some algae, differing from them mainly by the absence of 

 chlorophyll and the consequent inability to assimilate, the 

 separation into these two groups is to a large extent 

 physiological and not genetic. In order to designate the 

 assimilating thallophytes by a common name, the term 

 " algae ' is convenient, while for the bulk of the non- 

 assimilating groups " fungi " may be retained, but for 

 a systematic arrangement other characters of distinction 

 deserve the preference^. 



The Main groups of Thallophytes. 



Division I. Myxomycetes (Amoeboid plants). 



II. Schizomycetes (Bacteria). 



III. Schizophyceae (Blue-green Algae). 



IV. Flagellatae (Euglenaceae). 



V. Chlorophyceae (Green Algae) j. 



* First pointed out by F. Cohn (1872). 



■f- While the view here adopted by the author of this book has been warmly 

 supported by some eminent botanists, yet it may also be urged that, generally speaking, 

 the Algae and Fungi are only connected at one or two points and have, as a whole, 

 diverged markedly from one another in their more complex forms, structurally as well 

 as physiologically, w. T. s. 



I Excl. those in divisions VI and VII. 



