Nervous Impulse in Mimosa pudica

Abstract

Is the conduction of the excitatory impulse in the plant essentially similar to that of the nervous impulse in the animal? This problem is of great theoretical interest. In his “Nervous Mechanism of Plants”(1926), Bose states that the intercommunication and interaction between more or less distant organs in the plant are brought about, as in the animal, “in two different ways—by translocation of matter and by transmission of motion. The first is effected by the slow movement of fluid carrying chemical substances in solution, such as occurs in the circulation of sap; the second by the rapid propagation of protoplasmic excitation such as the nervous impulse in the animal”. In his presidential address at the Indian Science Congress, Lahore (1927), Bose makes his position perfectly clear by the statement that in physiological investigations the inquirer is primarily concerned with the function of the organ and not with its outward form. In support of this he adduces the case of insectivorous plants (Drosera, Dionä a, and Nepenthes) which are universally acknowledged to possess digestive organs, in spite of the fact that the organs are very different in appearance from those of the more complex animal. The employment of the same term for these plant and animal reactions is justified by the fact that the function of digestion is performed by similar processes in both: the solution of organic food-material by a glandular secretion, and the subsequent absorption of the dissolved product.