The manifestations of contractility by muscle are various in mode.
Another mode of manifestation of contractility by muscles is the rhythmic. A tendency to rhythmic contraction seems discoverable in almost all muscles.
The only physiological discovery which can be safely attributed to him is that of the contractility of the iris.
In favour of seeing in the lateral trunks and their branches a vascular system, is the contractility of the former, and the fact of the intrusion of the latter into the epidermis, matched among the Oligochaeta, where undoubted blood capillaries perforate the epidermis.