10S BRITISH EOCENE ELORA. 



It is well known that the lowest of all forms of life may be equally relegated to either 

 the animal or vegetable kingdoms. These, the Protista are either amorphous or composed 

 of cells filled with protoplasm, a complex living substance endowed with internal forces 

 conferring upon them variability, in other words, vitality. It is not improbable that the 

 earliest primordial plants may have possessed no higher organisation than this. There 

 are dredged, say Saporta and Marion, on the southern shores of France, creatures several 

 centimetres in length, whose substance is entirely penetrated with fine particles of 

 the sea-bottom. They would pass unnoticed did they not shift their position with 

 extreme slowness and vary their form by the extrusion and retraction of short prolonga- 

 tions. Placed in a glass of sea- water they attach themselves to the sides, and free themselves 

 gradually of sand, when a slightly yellow hyaline jelly, absolutely deprived of nucleated 

 elements, is disclosed. They are allied to the Protamceba and Pelobius, and from these 

 starting-points all the progressive stages of development are traceable. 



In certain of the Protista cellulose envelopes are developed, and when further 

 certain portions of the protoplasm become separated and assume a green colour, and are 

 thereby converted into chlorophyll, all the characters of vegetable life are realised. The 

 presence of this special substance gives rise to a whole series of new physiological 

 functions ; though present in some animals, it essentially characterises vegetable 

 life. A principal distinction between the two kingdoms is thus due at the outset 

 to the transformation of part of the elementary protoplasm into granules of chlorophyll. 



In progressing upward the structure of plants becomes increasingly complex, and 

 a nucleus appears in the cells. By gradual stages the Protophytes or Thallophytes 

 are reached, including the single-celled Desmids and Diatoms, with hard or soft 

 envelopes, the Confervae, Fucoids, the higher Algae, Elorideae, and Characeae. The 

 Fungi are destitute of chlorophyll, and hence, or owing to their parasitic and saprophytic 

 habits, any further development in them seems to have been arrested. 



While the more highly organised and complex Algae have retained the aquatic habits 

 necessary to their existence, some forms of Nostochinece, Pahnettece, and Vaucheria, seem 

 from time to time to have quitted the water to occupy humid places on land. These 

 furnish the earliest indication of adaptability to aerial life ; and it is curious to find this 

 proceeding from the lower types, but slightly differentiated from each other morpho- 

 logically, rather than from the higher types of Algae. Saporta and Marion assume that 

 when dry ground appeared some of the lower Algae with flat cellular fronds, such as Ulva, 

 gradually took possession of damp or marshy spots and, creeping face to the ground, 

 became ancestors of the Hepaticae ; x while others, more confervoid and possessing a thallus 

 with apical growth, have increased in complexity while adapting themselves to subaerial 



1 This is merely conjecture. Prof. Williamson, who has kindly looked through the proofs, reminds me 

 that the Hepaticae possess a thallus with apical growth (see Sachs, p. 347), and he has plants of Metzgeria 

 furcata showing it. 



