672 SCIENCE PROGRESS 



be incoordinate. In spite, however, of the fact that a breach 

 in the continuity of the nerves — the connexions between the 

 brain and the various parts of the body — involves a disturbance 

 or complete cessation of the usual responses to a stimulus 

 applied to a part of the body, still, so long as the cells are 

 alive, some measure of response is to be observed whenever a 

 stimulus is applied. If, for instance, a man sustain such 

 an injury that .the nervous connexion between his brain 

 and legs be cut off completely, he will draw up his legs if 

 the soles of his feet be tickled or pricked, though he will be 

 completely unconscious of the stimulus and of the reaction. 

 It is thus evident that co-ordination of parts still exists in a 

 region of the body which has no nervous connexion with 

 the brain, though it be of a lower and less complete kind. 



If we go lower in the animal kingdom, we find that forms 

 of co-ordination continue in the body of the organism after 

 the destruction of parts of the brain which if effected in man 

 would have destroyed the same forms of co-ordination. In a 

 frog, for instance, the destruction of parts of the brain which 

 would cause immediate death in man leaves a frog with almost 

 a full complement of co-ordinate responses to stimuli. 



If a muscle with the nerve supplying it be removed from the 

 leg of a frog and the nerve be stimulated, the muscle contracts ; 

 moreover, the particular kind of contraction produced depends 

 upon the kind of stimulus applied. Here we have a lower form 

 of co-ordination but still co-ordination of the same order. 



In the lowest forms of multicellular animals a nervous system 

 does not exist but we find an insensible gradation in co-ordinate 

 phenomena between the most complex observed in man and 

 those observed in animals in which there is no nervous system. 

 Co-ordination, in fact, obviously exists quite independently 

 of a nervous system. Plants will grow towards the light and 

 react as whole individuals to various other stimuli. Much more 

 striking examples may be found in particular plants. In Drosera, 

 for example, the leaves are provided with numerous tentacles 

 having glandular enlargements at their ends. The tentacles 

 around the margin of the leaf are long, those in the middle 

 are short. The glands secrete a quantity of a glistening and 

 sticky substance which insects mistake for dew or honey and 

 are attracted. If one of the short tentacles be stimulated, all 

 the long peripheral tentacles bend over so that their enlarged 



