by very refined methods of experiment, has shewn that plant-growth really proceeds by tiny and perfectly rhythmical pulsations recurring at regular intervals of a few seconds of time. Fig. 17 shews, according to Boseãs observations37, the growth of a crocus, under a very high magnification. The stalk grows by little jerks, each with an amplitude of about ôñ002 mm., every {88} twenty seconds or so, and after each little increment there is a partial recoil.
The rate of growth of various parts or organs .
The differences in regard to rate of growth between various parts or organs of the body, internal and external, can be amply illustrated in the case of man, and also, but chiefly in regard to external