THE GROUPS AND ANCESTRY OF ORGANISMS 



101 



increase in sporophyte size with an over-all general 

 increase in plant size. Final land specializations 

 were two in number: (1) still greater freedom from 

 dependence upon water when seed plants obtained 

 pollen tubes for fertilization and (2) the develop- 

 mental series of seed plants from trees to shrubs, to 

 herbs, and finally to annuals from perennial plants. 

 This developmental sequence was associated with 

 the evolution of dormant seeds. 



The above assumptions of "'major steps" provide 

 a basis for segregation of the main taxa of the King- 

 doms Monera, Protista, and Plantae. 



Kingdom Monera — protoplasmic organization, nucleus 

 incompletely developed; reproduction 

 chiefly, probably strictly, asexual 



A. Chlorophyll absent; chiefly parasitic 

 PHVLCM scHizoPHYT.Ji (Bacteria) 



B. Chlorophyll present; chiefly free-living 

 PH'iLLM cv.-\NOPHVT.\ (Blue-gpecn Algae) 



Kingdom Protista — unicellular to cellular organization, 

 nucleus completely developed; repro- 

 duction asexual and sexual; chiefly 

 aquatic, require water medium for 

 fertilization; chlorophyll present or 

 absent 

 suBKiNGDOM PROTOZO.A — uniccUular organization, often 

 colonial; chlorophyll only in 

 some flagellates 



A. Locomotion by one or more whip-like structures 

 (flagellae) 



PHYLLM FLACELLAT.^ (= mastigophor.a) (Flagel- 

 lates) 



B. Locomotion and food capture by irregular, elongate 



body extensions (pseudopodia) that are created by 

 protoplasmic flow 



PHYLL-M SARCODIN.^ (= RHIZOPOD.\) 



C. All internal parasites; without any means of locomo- 



tion 



PHYLLM SPOROZO.\ 



D. Locomotion by a more or less extensive covering of 



hair-like structures (cilia), or organism possesses 

 sucking tentacles and regularly is attached by a 

 stalk to the substrate 



PH\ LLM CILIOPHORA (CiliatCS) 



SLBKINCDO.M FLNGi — Unicellular to cellular with in- 

 cipient tissue formation; locomo- 

 tion by flagellae or pseudopodia, or 

 non-motile; chlorophyll absent 



A. Body multinucleate, essentially naked protoplasm 

 PHYLL^M MVXOMYCOPH\TA (Slime Molds or Fungi) 



B. Unicellular, cellular, or approach greater complexity, 



usually filamentous 



PHYLl M ELMYCOPHYTA (TrUC Fungi) 



Kingdom Plantae — cellular, tissue, or organ organiza- 

 tion; chlorophyll typically present; 

 characteristically nonmotile as adults; 

 most require an external water me- 

 dium for fertilization 

 SUBKINGDOM ALGAE — Cellular and tissue organization, 

 sometimes unicellular; chiefly 

 aquatic, require a water medium 

 for fertilization; life cycles of all 

 types 



A. Cellular organization or mostly so, some unicellular 



1. Plastids grass green 



a. Without sex organs 



PHYLLM CHLOROPHYTA (Green Algae) 



b. With sex organs 



PHYLUM CHAROPHYTA (Stoneworts) 



2. Plastids usually yellow to brown; cellulose silici- 



fied 

 PHYLUM CHRYSOPHYTA (Golden Algae) 



B . More complex cellular or tissue organization 



1. Tissues present; incipient organ formation 

 PHYLUM PHAEOPHYTA (Brown Algae) 



2. Only approach tissue differentiation 

 PHYLUM RHODOPHYTA (Red Algae) 



SUBKINGDOM EMBRYOPHYTA — organs present, tissue or 



organ organization; chiefly 

 terrestrial, moisture re- 

 quired for fertilization; life 

 cycle usually with definite 

 alternation of generations 

 (diplobiontic) 



A. No veins; sporoph>ie small; in moist areas, require 



water medium for fertilization; mostly tissue 

 organization 

 PHYLUM BR'iDPH^TA (Livcrworts and Mosses) 



B. Veins present; sporoph\le definitely dominant; in- 



cludes most land plants, fertilization requires that 

 plant have sufficient internal moisture; organ 

 organization 

 PHYLUM TRACHEOPHYTA (Vascular Plants) 



ANIMAL COMPLEXITY 



The trends in animal evolution were and are so 

 many that the structural features of many species 

 are extremely complex. Considering this complexity, 

 it is fortunate that only a few anatomical and other 

 characteristics are needed to separate the phyla and 

 to indicate their possible paths of evolution. The five 

 main features are grade of organization, development, 

 symmetry, body cavities, and segmentation. In dis- 

 cussing them no attempt will be made to imply se- 

 quences of events. This is not necessary because the 

 sequence of each is generally believed to be from the 

 simple to the complex. 



