WHAT IS A PLANT? 163 



that this may not be also said of Spongilla and Hydra, though 

 this is not definitely proven. 



Mr. Geddes points out that there is a strange parallel between 

 the Drosera — which, while imitating a carnivorous animal, tends 

 to lose its normal character by possessing so tiny a root — and the 

 Convoluta — which, imitating a green plant, loses all trace of an 

 alimentary canal, and is of exceedingly abstemious habits. 



We see, therefore, that even the nature of the food, as a dis- 

 tinctive mark, fails us in some cases on both sides ; many plants 

 needing more complex bodies for food, many appearing to subsist 

 on ready-made protein, while some, possibly, could not live 

 without it ; some few animals seeming to possess the plant-power 

 of decomposing carbonic acid. 



However, we may say that, pJiysiologically, the most distinctive 

 feature of plant-life is the power to manufacture protein from less 

 complex bodies ; that of animal-life, the absence of such power. 



Let us now gather up our evidence, and see what reply, if any, 

 we may give to the query at the head of this paper. Looking 

 carefully through the eleven sections, and marking their details, 

 we find the case to be pretty much this : — In form, in the presence 

 of starch, or of chlorophyll, in power of locomotion, in the pre- 

 sence of circulatory organs, or of the body called nitrogen, in the 

 functions of respiration and sensation, we can by no means find 

 diagnostic characters ; i7i the presence of a cellulose coat in the 

 plant-cell, in digestion follo-zaed by absorption, and in the power to 

 manufacture p7'otein, we find fairly constant and well-marked dis- 

 tinctions ; the morphological feature of plants being this cellulose 

 coat ; of animals, its absence ; the physiological peculiarity of 

 plants, this manufacturing power ; of animals, the want of it. 



Finally, seeing that some plants are devoid of the power to 

 manufacture protein out of the simple compounds, requiring those 

 more complex ; that some appear to feed on protein, as such ; 

 remembering the cases of ^-Ethalium, and also of the " Monads," 

 bearing in mind the example of Convohita, and possibly others 

 among animals : we are compelled to admit that in many cases 

 the difference is one of degree rather than of kind, and that to the 

 question. Is this an animal or a plant ? we must often reply, IVe 

 do not know / 



