Physiol. and Path. [L. tonus, a. Gr. τόνος TONE.]
1. The condition or state of muscular tone; the proper elasticity of the organs; tonicity.
1876. trans. Wagner’s Gen. Pathol. (ed. 6), 162. In a reflex manner the arterial tonus is reduced or increased.
1882. Burdon Sanderson, in Lancet, 29 April, 678. The paralysed artery recovers, and sometimes over-recovers its normal state of contraction, or, as we call it, its tonus. Tonus … is one of the independent endowments of arteries.
1899. Allbutt’s Syst. Med., VII. 109. Whence comes this loss of tonus?
2. A tonic spasm.
1891. in Cent. Dict.
1899. Allbutt’s Syst. Med., VII. 890. The clonic spasm may … pass into slight tonus of very short duration.
1899. Syd. Soc. Lex., Tonus, tonic spasm.
3. (See quot.)
1902. Encycl. Brit., XXXI. 740/1. A continuous lesser ‘change’ or stream of changes sets through the neuron, and is distributed by it to other neurons in the same direction and by the same synapses as are its nerve impulses. This gentle continuous activity of the neuron is called its tonus.
4. Comb., as tonus-producing adj.
1897. Allbutt’s Syst. Med., III. 317. Any failure of the circulation dependent upon the absence from the blood-stream of this tonus-producing substance.
