76 WHAT IS A PLANTS 



same time to confess the hopelessness of research and the futility 

 of work. As Professor Huxley aptly observes, "To form this 

 biological ' No-man's Land ' simply doubles the difficulty, which 

 before was single," because we must take a scientific census of 

 this new kingdom, in order to define and classify its members. 

 Still, the very proposal indicates the difficulties in which modern 

 biologists are placed. 



We will glance seriatim at the various distinctions, which from 

 time to time have been supposed to exist ; in so doing, we shall 

 see how, by exceptions on one side or on both, they successively 

 fail to be diagnostic, if we are to include all forms of life, until we 

 are reduced to so narrow a ground, that in the lowest and most 

 minute organisms certainly, and even among some of the higher 

 and more complex forms, the difference between a plant and an 

 animal comes to be one of degree rather than of kind. 



I. — Form. This, although a safe guide among the higher 

 types, fails as we descend the scale. Thus, among animals, the 

 Sponges, belonging to the sub-kingdom, Porifera, resemble plants 

 in their external form, and were for some time classed as such. 

 Among the Ccelenterata^ we find the graceful silver Sertularia, 

 or Sea-Fir ; the Pennatula, or Sea-Pen, with its feathery branches, 

 phosphorescent on irritation ; the Gorgonia^ or Sea-Shrub, whose 

 spicules are familiar to all microscopists ; the Coralliitm, or Red 

 Coral, and its allies ; (the term " Zoophytes," or plant-like ani- 

 mals, is to this day applied to these last four and others of a 

 similar nature ; ) while higher still, among the Polyzoa, we find 

 Flustra, the Sea-Mat, which is, perhaps, the best-known case of 

 resemblance. Flustra is a pale-brown, arborescent organism 

 gathered every summer at the seaside, and dried as a " sea-weed," 

 usually not named by the finder, because he is unable to detect its 

 photograph anywhere in the sea-weed books. He does not 

 know that it is, in reality, a " colony " of comparatively highly- 

 organised animals, each in its own cell, each provided with a crown 

 of tentacles for seizing its prey, and each having a mouth, stomach, 

 nervous system, and other organs ! 



On the plant-side, there are certain of the Algae, or water-weeds, 

 microscopic forms, which, during part of their fife, develop tiny, 

 hair-like processes, called cilia, by which they propel themselves 



