ii LIVING MATTEE 53 



to all living beings, we may formulate the following general 

 propositions : 



(a) All vital activity is founded on the metabolism of living 

 matter. 



(6) As a material exchange, metabolism expresses itself in 

 anabolic and katabolic processes. 



(c) As a dynamic exchange, metabolism manifests itself by the 

 accumulation and discharge of energy. 



(cT) The anabolic and katabolic processes express themselves 

 in the phenomena of nutrition (consumption and repair) and 

 reproduction (formation and evolution of germs). 



() The accumulation and transformation of energy is exhibited 

 in the phenomena of rest and excitation (automatic or reflex in 

 character). 



(/) All the processes of vital metabolism conform to the 

 conservative laws of heredity, and to the evolutionary laws of 

 variability. 



(</) Vital metabolism is exhibited under a double aspect : 

 to external observation it manifests itself in somatic phenomena ; 

 to introspection it reveals itself in psychical phenomena, conscious 

 and unconscious. 



V. On penetrating deeper into the study of common vital 

 activities, we must inquire whether, from the standpoint of general 

 physiology, it is possible to differentiate sharply between the two 

 great kingdoms of living nature plants, and animals. 



In comparing what are relatively the highest representatives 

 of the two kingdoms, nothing seems more simple and natural than 

 the distinction between a plant and an animal. Many erroneous 

 opinions have, nevertheless, been promulgated in the attempt to 

 define their differential characters. Of these the principal are as 

 follows : 



According to Linnaeus, the lack of sensibility and capacity 

 for active movement in plants is sufficient to distinguish them 

 from animals. But the case of Mimosa pudica (Fig. 9), Dionea 

 muscipula (Fig. 10), and other sensitive plants, whose leaves 

 move at the slightest contact with an insect, show that excitation 

 in the form of active movement, the external sign of sensibility, 

 is demonstrable in plants also. Claude Bernard (1878) showed 

 that anaesthetics (ether and chloroform) act in the same way on 

 animals and on sensitive plants. 



Cuvier was of opinion that the existence in animals of a 

 distinct digestive apparatus with the accompanying digestive 

 function, of which no trace exists in plants, was a sufficient sign 

 of distinction between the former and the latter. To-day, however, 

 we know that an immense number of the lower animals have no 

 digestive tube, while on the other hand the so-called insectivorous 

 plants, described by Darwin, possess organs capable of subjecting 



