OF ORGANIZED BEINGS. 415 



some irritability. If the leaves of a sensitive plant are 

 touched they immediately shrink, and with the branches 

 to which they are attached bend towards the earth. The 

 leaves of the moving plant, a native of the East Indies, 

 are so excited by the rays of the sun that they are con- 

 stantly in motion while exposed to them. The plant 

 called Dionca muscipula or Venus' fly trap, affords an- 

 other example of rapid vegetable motion. The leaves of 

 this plant are armed with rows of small prickles, and are 

 covered by small glands which secrete a sweetish liquid 

 that is extremely pleasant to flies. When a fly comes in 

 contact with a leaf the two lobes rise up, the prickles are 

 fastened together, and the unwary animal is destroyed. 

 The motion of animals is somewhat influenced by their 

 specific gravity. A flea can leap some hundred times its 

 length, and spiders and worms fall with impunity from 

 immense heights. If large animals should leap or fall 

 as far in proportion to their weight or gravity, they would 

 be crushed to atoms. 



We have said that the voluntary muscles were under 

 the control and influence of the will. The question may 

 now be asked from what organ does the will emanate, 

 and what are the means of communication between that 

 organ and the muscles? The brain which is contained 

 within the bony cranium is allowed by all to be the seat 

 where all the faculties of the mind in man and of instinct 

 in animals reside. From the brain and spinal column 

 (which is a mere continuation of the brain) proceed 

 fortytwo pair of shining inelastic cords called nerves, 

 which differ from each other in size, color, and consist- 

 ence. These nerves send off innumerable branches 

 which are distributed like a net work over every part of 

 the body. They are the immediate organs of sensation 

 as well as of muscular motion. If the nerves which go 

 to the arm were cut off, the muscles below the incision 

 would lose all power of motion, and the skin of sensation. 

 If the nervous communication between the brain and the 

 eye, or ear, or tongue, were cut off, we could no more 

 see, or hear, or taste. When we receive an impression 

 on the finger, this impression is conveyed to the brain by 

 means of nerves, and the mind takes cognizance of it. 



