CONSTITUTION OF THE ANIMAL AND PLANT KINGDOMS. 59 



Lichens and Fungi ; whilst no botanist questions the idea that the 

 ferns, club-mosses, and their neighbours, lead the way from the lower 

 or "flowerless" plants to the Gymnosperms (or firs, pines, &c.) 

 amongst the " flowering " plants. Between the Monocotyledons and 

 Dicotyledons, again, there are obvious links, and hence we discover 

 that the whole plant kingdom may be regarded as being bound 

 together after the actual fashion of its own product seen in the 

 tree, which, whilst possessing its individual parts, likewise exhibits a 

 continuity of development that forms one of the chief characteristics 

 alike of the single organism, and of its relationship with its neigh- 

 bours. 



In the lowest deeps of plant life we may discover organisms 

 which possess at the best a doubtful title to be regarded as the 

 objects of botanical study. In the animal world, likewise, are 

 included lower organisms which may be regarded in certain aspects 

 as possessing true relationships with plants. Modern biology to-day 

 frankly admits its inability to pronounce whether certain lowest 

 forms of life are animals or plants. Certain " monads," for example, 

 consisting each of a speck of protoplasm provided with the 

 microscopic whip- tails, exhibit a highly confusing identity of 

 structure and function, which renders their exact nature indeter- 

 minable, or at least highly doubtful. Hence we discover that 

 apparently at the lowest confines of the animal and plant realms we 

 enter a " biological ' No man's land,' " whereof the included in- 

 habitants may legitimately claim relationship with both kingdoms. 

 They exhibit in this latter respect, in the eyes of the biologist, the 

 actual survivals of that early epoch in the history of life's develop- 

 ment when the specialised kingdoms of animals and plants were not, 

 and when existence passed placidly along the common lines which 

 were soon to diverge into the two great series of living beings that 

 environ our footsteps to-day. 



The great lesson which a study of the constitution of the living 

 worlds is calculated to teach the independent observer may be 

 summed up in the contention that the entire subject testifies to the 

 continuous and connected nature of the development of life at large. 

 The beginnings of higher and lower life alike, are represented by 

 humble stages, wherein specks of protoplasm, or at the most simple 

 " cells," discharge all the functions of existence. From such simple 

 beginnings the highest being is developed. The difference between 

 the highest and lowest organism is therefore not so much one of 

 kind as of the degree of perfection to which elaboration and develop- 

 ment has carried the living form. We may be unable definitely to 

 indicate why one organism speeds along this pathway to assume a 

 place in one type, or why another, apparently identical in its early 

 life with the first, should develop into a widely different being. 



