500 VOLUNTARY MOTION. 



same are perceptible in dried anatomical preparations ; and Ras- 

 pail by repeated boiling effected them in fecula, converting it into 

 caseic acid. If fresh muscle is exposed for some time to water, 

 or kept in moist earth, the fibrine disappears, and a white fatty 

 matter remains called adipocire : but this is usually ascribed to a 

 change of the fat in the muscle. Muscle may perhaps be changed 

 during life into fat, for we possess in University College diseased 

 muscles, in which each fibre is replaced by a string of fat. Fi- 

 brine abounds most in the muscles of the old. 



Besides the vital movements which probably occur in the vessels and cellular 

 texture of plants, and those which occur slowly in the stalks and tendrils of 

 annuals which cling, and in leaves, we observe the flowers and leaves of many 

 plants stand up open in the day and fall or close at night. On the approach 

 of a storm, the leaves of most plants with delicate stamina become erect, so that 

 white flowered meadow trefoil is a barometer to the Swedes. Artificial light will 

 make the flowers and leaves of some plants expand at night, and removal to a 

 dark place in the day time make them droop ; while the approach of hot iron to 

 their upper surface will make some leaves erect. Cold and narcotics lessen or 

 destroy, while all stimuli augment, these movements, which are more vigorous 

 in the young than in the old. Even mechanical irritation, perhaps a mere touch, 

 will cause motions in the leaves of mimosae ; and the motion will spread from 

 the one irritated to other leaves successively, and the petiole, and at last the 

 foot-stalk itself, descends. The lobes of the leaves of the dionaea muscipula have 

 stiff hairs on their edge, and close instantly upon a hapless insect which lights upon 

 them ; and, as each lobe of the leaf has three thorns, the poor thing is not only 

 imprisoned but impaled on the spot : and, what is still more cruel and corresponds 

 in design with the craftiness of animals, as that does with their destructiveness, 

 the leaf is supplied with glands which secrete sugar and thus tempt the instinct 

 of the poor thing. The small lateral leaves of the hedysarum gyrans and cus- 

 pidatum are in incessant motioti. Some flowers contract on mechanical irri- 

 tation. The stamina and pistils of flowers, but especially the stamina, perform 

 many varieties of motion, and also obey external stimuli, and are influenced by 

 poisons.* 



The voluntary motions are the distinguishing characteristics of the animal 

 from the vegetable kingdom. For no plant has been discovered procuring for 

 itself food by means of voluntary motion ; nor any animal incapable of loco- 

 motion, or at least of procuring sustenance by the voluntary motion of individual 

 members. 



Muscles exist in animals of all classes, from the mammifera to the radiaria. 



* Consult Dr. Tiedemann, 1. c. cccclxxiii. sqq. 



