Portion, where the proboscis, floating in P.o., Exterior opening its sheath, is attached with it to the through which the muscular tissue of the head (fig.
The muscular tissue of the dorsal body-wall is much reduced and the integument here is thin and FIG.
The muscle-fibres arise as processes from the bases of the epithelial cells; such cells may individually become sub-epithelial in position, as in the polyp; or, in places where muscular tissue is greatly developed, as in the velum or sub-umbrella, the entire muscular epithelium may be thrown into folds in order to increase its surface, so that a deeper sub-epithelial muscular layer becomes separated completely from a more superficial bodyepithelium.
In the Gastropoda the muscular tissue of the buccal mass is coloured red by haemoglobin.
The muscular tissue of the Hydromedusae is entirely ectodermal.
The muscular tissue consists primarily of processes from the bases of the epithelial cells, processes which are contractile in nature and may be distinctly striated.
External epithelium is flat on the ex-umbral surface, more columnar on the sub-umbral surface, where it forms the muscular tissue of the sub-umbrella and the velum.
It may here be stated that the non-striped muscular tissue of the bladder, the uterus and the spleen is also stimulated, as well as that of the iris (see below).
The active contraction of muscular tissue has no counterpart in the plant.
The secretion of mucus by the bronchi and trachea is greatly reduced and their muscular tissue is paralysed - a fact of which much use is made in practical medicine.